scholarly journals Temperature Control ofpsaAExpression by PsaE and PsaF inYersinia pestis

2019 ◽  
Vol 201 (16) ◽  
Author(s):  
Joshua D. Quinn ◽  
Eric H. Weening ◽  
Taryn A. Miner ◽  
Virginia L. Miller
Keyword(s):  
High Temperature ◽  
Posttranscriptional Regulation ◽  
Yersinia Pseudotuberculosis ◽  
Bacterial Pathogen ◽  
Mammalian Host ◽  
Bubonic Plague ◽  
Content Type ◽  
Environmental Signals ◽  
The Stability ◽  
The Impact

ABSTRACTPsaA, the subunit of the fimbria originally referred to as the “pH 6 antigen,” is required for full virulence ofYersinia pestisduring bubonic plague. The expression ofpsaAis dependent upon specific environmental signals, and while the signals (high temperature and acidic pH) are defined, the mechanisms underlying this regulation remain unclear. In the closely related speciesYersinia pseudotuberculosis,psaAtranscription requires two regulatory genes,psaEandpsaF, and it is speculated that posttranscriptional regulation of PsaE and/or PsaF contributes to the regulation ofpsaAtranscription. Few studies have examined the regulation ofpsaAexpression inY. pestis, and prior to this work, the roles ofpsaEandpsaFinY. pestishad not been defined. The data presented here show that bothpsaEandpsaFare required forpsaAtranscription inY. pestisand that the impact of temperature and pH is mediated through discrete posttranscriptional effects on PsaE and PsaF. By generating antibodies that recognize endogenous PsaE and PsaF, we determined that the levels of both proteins are impacted by temperature and pH. High temperature is required forpsaEandpsaFtranslation via discrete mechanisms mediated by the mRNA 5′ untranslated region (UTR) upstream of each gene. Additionally, levels of PsaE and PsaF are impacted by pH. We show that PsaF enhances the stability of PsaE, and thus, both PsaE and PsaF are required forpsaAtranscription. Our data indicate that the environmental signals (temperature and pH) impact the expression ofpsaAby affecting the translation ofpsaEandpsaFand the stability of PsaE and PsaF.IMPORTANCEY. pestisis a Gram-negative bacterial pathogen that causes bubonic plague. As a vector-borne pathogen,Y. pestisfluctuates between an arthropod vector (flea) and mammalian host. As such,Y. pestismust recognize environmental signals encountered within each host environment and respond by appropriately regulating gene expression. PsaA is a keyY. pestismammalian virulence determinant that forms fimbriae. Our work provides evidence thatY. pestisutilizes multiple posttranscriptional mechanisms to regulate the levels of two PsaA regulatory proteins in response to both temperature and pH. This study offers insight into mechanisms that bacteria utilize to sense environmental cues and regulate the expression of determinants required for mammalian disease.

Consumer responses to the failure of self-service banking technology: moderating role of failure stability

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nedra Bahri Ammari ◽  
Abir Hsouna ◽  
Mounia Benabdallah ◽  
Anish Yousaf ◽  
Abhishek Mishra
Keyword(s):  
Word Of Mouth ◽  
Positive Impact ◽  
Negative Word ◽  
The Self ◽  
Content Type ◽  
Consumer Dissatisfaction ◽  
Self Service ◽  
The Stability ◽  
Self Service Technology ◽  
The Impact

PurposeThe purpose of this study is to investigate the impact of dissatisfaction and anger, driven by the failure of the self-service technology of banks, on customers' post-purchase behavioural reactions, such as complaints, negative word-of-mouth (NWOM) and supplier change. The stability of the failure is proposed to moderate these relationships.Design/methodology/approachThe proposed research model was tested through data collected from an online survey of a Tunisian sample of 300 respondents, using the scenario method.FindingsThe study validates the positive impact of dissatisfaction on anger and negative word-of-mouth, as well as that of anger on complaint behaviour and negative word-of-mouth. The relation between dissatisfaction and negative word-of-mouth is mediated by anger. When the failure is stable, dissatisfied users of the self-service technology seek to enhance their negative word-of-mouth and supplier change. The results also show that the stability of the failure enhances the effect of anger on complaint behaviour.Practical implicationsBanks should invest efforts to accelerate the recovery of services to reduce consumer dissatisfaction and anger and prevent adverse behavioural outcomes. Further, they need to ensure that failures are not repeated, as failure stability activates some otherwise non-significant behavioural outcomes, like supplier change.Originality/valuePrevious works have focused on the impact of dissatisfaction and negative emotions for interpersonal services, but very few works have come to associate dissatisfaction, anger, complaint, negative word-of-mouth and supplier change in an integrative framework for an self-service technology failure.

Dosimetric evaluation of methyl red radiochromic film for radiation processing

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Awad AL Zahrany ◽  
Khalid Rabaeh ◽  
Molham Eyadeh ◽  
Ahmed Basfar
Keyword(s):  
Gamma Ray ◽  
Dose Range ◽  
Absorbed Dose ◽  
Radiochromic Film ◽  
High Dose ◽  
Methyl Red ◽  
Radiation Processing ◽  
Content Type ◽  
The Stability ◽  
The Impact

Purpose The purpose of this paper is to present a radiochromic film dosimeter containing polyvinyl alcohol (PVA) matrix and various concentrations of methyl red (MR) dye for high dose measurements. Design/methodology/approach The MR-PVA films were exposed to irradiation up to 60 kGy using 60Co source of gamma ray. The ultraviolet and visible regions (UV/VIS) spectrophotometry were used to examine the optical density of pre-and post-irradiated dosimeters at 424 nm. Findings The dose sensitivity of MR-PVA films increases significantly with increasing MR dye concentrations in the dose range of 5 to 60 kGy. The impact of relative humidity, irradiation temperature, dose rate and the stability of the films has been analyzed. The overall uncertainty of the MR-PVA film dosimeter is 6.12% (Double Standard-deviation, 95% confidence level). Practical implications It was found that the MR-PVA films may be used as high dose dosimeter with an acceptable overall uncertainty in routine industrial radiation processing. Originality/value The color bleaching of irradiated MR-PVA films in terms of specific absorbance curves increases significantly with increasing absorbed dose up to 60 kGy.

Knowledge diversity and firm performance: an ecological view

2016 ◽  
Vol 20 (4) ◽  
pp. 671-686 ◽  
Author(s):  
Deng-Neng Chen ◽  
Ting-Peng Liang
Keyword(s):  
Knowledge Management ◽  
Firm Performance ◽  
Organizational Performance ◽  
Company Performance ◽  
Content Type ◽  
Knowledge Diversity ◽  
Ecological View ◽  
New Perspective ◽  
The Stability ◽  
The Impact

Purpose Knowledge has been considered a crucial organizational asset for gaining competitive advantages. It is critical for a firm to maintain a knowledge composition that is productive. This study aims to examine the applicability of the diversity–stability principle in ecology to knowledge management and further investigate the impact of knowledge diversity on firm performance. Design/methodology/approach A theoretical framework for knowledge diversity and firm performance is proposed; a questionnaire survey was conducted to evaluate the research framework. Fifty-eight valid responses from experts were collected to measure knowledge strength and diversity of 20 enterprises in four industries, and financial indexes of the 20 enterprises from 2008 to 2012 were collected to analyze the research model. Findings The results show that higher information technology (IT) capabilities in a firm lead to higher levels of knowledge strength and diversity. The strength and diversity of knowledge in a company can improve average company performance and reduce performance variations. Research limitations/implications This paper presents a new perspective that applies the ecological concept of diversity to examine the value of knowledge in organizations. The findings expand our understanding of the role of IT and knowledge in organizational performance. A limitation is that the sample size is relatively small, which may limit the generalizability of the findings. Practical implications CEOs and chief knowledge officers can apply the findings herein to assess their organizational knowledge profiles and maintain a healthy knowledge ecology in strategic planning. They should be aware that both knowledge strength and knowledge diversity are crucial to the stability of firm performance. Originality/value The ecological view of knowledge management stresses the importance of maintaining a healthy intensity and diversity of knowledge at the macro level and indicates a new direction for knowledge management.

scholarly journals After the Fact(or): Posttranscriptional Gene Regulation in EnterohemorrhagicEscherichia coliO157:H7

2018 ◽  
Vol 200 (19) ◽  
Author(s):  
Amber B. Sauder ◽  
Melissa M. Kendall
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Posttranscriptional Regulation ◽  
Posttranslational Regulation ◽  
Content Type ◽  
Infectious Dose ◽  
Posttranscriptional Gene Regulation ◽  
Niche Adaptation ◽  
Intestinal Pathogen ◽  
The Stability

ABSTRACTTo adapt to ever-changing environments, pathogens quickly alter gene expression. This can occur through transcriptional, posttranscriptional, or posttranslational regulation. Historically, transcriptional regulation has been thoroughly studied to understand pathogen niche adaptation, whereas posttranscriptional and posttranslational gene regulation has only relatively recently been appreciated to play a central role in bacterial pathogenesis. Posttranscriptional regulation may involve chaperones, nucleases, and/or noncoding small RNAs (sRNAs) and typically controls gene expression by altering the stability and/or translation of the target mRNA. In this review, we highlight the global importance of posttranscriptional regulation to enterohemorrhagicEscherichia coli(EHEC) gene expression and discuss specific mechanisms of how EHEC regulates expression of virulence factors critical to host colonization and disease progression. The low infectious dose of this intestinal pathogen suggests that EHEC is particularly well adapted to respond to the host environment.

The impact of long-term riskless asset on ensuring liquidity and preventing banking fragility

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mahmoud Shahin
Keyword(s):  
Risk Sharing ◽  
Content Type ◽  
Asset Portfolio ◽  
Illiquid Asset ◽  
The Stability ◽  
Gain Loss ◽  
Riskless Asset ◽  
The Impact ◽  
Liquidation Cost

PurposeThrough portfolio diversification, the author identifies the risk sharing deposit contract in a three-period model that maximizes the ex ante expected utility of depositors.Design/methodology/approachIn this paper, the author extends the study by Allen and Gale (1998) by adding a long-term riskless investment opportunity to the original portfolio of a short-term liquid asset and a long-term risky illiquid asset.FindingsUnlike Allen and Gale, there are no information-based bank runs in equilibrium. In addition, the model can improve consumers' welfare over the Allen and Gale model. The author also shows that the bank will choose to liquidate the cheaper investments, in terms of the gain-loss ratios for the two types of existing long-term assets, when there is liquidity shortage in some cases. Such a policy reduces the liquidation cost and enables the bank to meet the outstanding liability to depositors without large liquidation losses.Originality/valueThe author believe that the reader would be interested in this article because it is relevant to real world where depositors rush to withdraw their deposits from a bank if there is negative information about future prospect of the bank asset portfolio and bank investment. Economists and financial analysts need to determine the suitable mechanism to improve the stability of the bank and the depositor welfare.

scholarly journals Strengthening the stability of exports through GVC participation

2018 ◽  
Vol 45 (3) ◽  
pp. 610-637 ◽  
Author(s):  
Carmen Díaz-Mora ◽  
Rosario Gandoy ◽  
Belen Gonzalez-Diaz
Keyword(s):  
Developing Countries ◽  
Value Chain ◽  
Value Added ◽  
Time Duration ◽  
Content Type ◽  
Country Level ◽  
Key Factor ◽  
Trade Relationships ◽  
The Stability ◽  
The Impact

Purpose Drawing on the literature that has shown the prevalence of short-lived trade relationships, the purpose of this paper is to provide further understanding about this issue by exploring the impact of engaging in Global Value Chains (GVCs) on the chance of export survival at product-country level, paying special attention to the differences between advanced and developing countries. The authors also investigate whether the type of GVC participation (backward or forward) matters for export survival. Design/methodology/approach To capture to what extent a country’s exports are integrated in GVCs, the authors use the OECD Inter-Country Input-Output database to estimate value added incorporated in exports. Through the estimation of a discrete-time duration model, the authors explore the impact of engaging in GVCs on export survival using highly disaggregated trade data from the CEPII’s BACI database. Findings The findings endorse the hypothesis that deeper participation in GVCs is a key factor in explaining stability in trade relationships, mainly for developing countries where the trade flows are especially fragile. The authors also find different effects depending on the type of GVC involvement and on whether the value chain partners are advanced or developing. Originality/value The paper contributes to the literature by extending the understanding on the factors that promote the stability of exports, including among them, involvement on GVCs (and its forms) which is one of the most relevant factors to explain recent behavior of trade.

scholarly journals Glycolytic Dependency of High-Level Nitric Oxide Resistance and Virulence in Staphylococcus aureus

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Nicholas P. Vitko ◽  
Nicole A. Spahich ◽  
Anthony R. Richardson
Keyword(s):  
Nitric Oxide ◽  
Staphylococcus Aureus ◽  
Innate Immunity ◽  
Bacterial Pathogen ◽  
No Production ◽  
Low Oxygen ◽  
Acid Fermentation ◽  
Independent Manner ◽  
Content Type ◽  
The Impact

ABSTRACTStaphylococcus aureusis a prolific human pathogen capable of causing severe invasive disease with a myriad of presentations. The ability ofS. aureusto cause infection is strongly linked with its capacity to overcome the effects of innate immunity, whether by directly killing immune cells or expressing factors that diminish the impact of immune effectors. One such scenario is the induction of lactic acid fermentation byS. aureusin response to host nitric oxide (NO·). This fermentative activity allowsS. aureusto balance redox during NO·-induced respiration inhibition. However, little is known about the metabolic substrates and pathways that support this activity. Here, we identify glycolytic hexose catabolism as being essential forS. aureusgrowth in the presence of high levels of NO·. We determine that glycolysis supportsS. aureusNO· resistance by allowing for ATP and precursor metabolite production in a redox-balanced and respiration-independent manner. We further demonstrate that glycolysis is required for NO· resistance during phagocytosis and that increased levels of extracellular glucose limit the effectiveness of phagocytic killing by enhancing NO· resistance. Finally, we demonstrate thatS. aureusglycolysis is essential for virulence in both sepsis and skin/soft tissue models of infection in a time frame consistent with the induction of innate immunity and host NO· production.IMPORTANCEStaphylococcus aureusis a leading human bacterial pathogen capable of causing a wide variety of diseases that, as a result of antibiotic resistance, are very difficult to treat. The frequency ofS. aureustissue invasion suggests that this bacterium has evolved to resist innate immunity and grow using the nutrients present in otherwise sterile host tissue. We have identified glycolysis as an essential component ofS. aureusvirulence and attribute its importance to promoting nitric oxide resistance and growth under low oxygen conditions. Our data suggest that diabetics, a patient population characterized by excess serum glucose, may be more susceptible toS. aureusas a result of increased glucose availability. Furthermore, the essential nature ofS. aureusglycolysis indicates that a newly developed glycolysis inhibitor may be a highly effective treatment forS. aureusinfections.

scholarly journals Type III Secretion System-Dependent Translocation of Ectopically Expressed Yop Effectors into Macrophages by Intracellular Yersinia pseudotuberculosis

2011 ◽  
Vol 79 (11) ◽  
pp. 4322-4331 ◽  
Author(s):  
Yue Zhang ◽  
Galina Romanov ◽  
James B. Bliska
Keyword(s):  
Cell Death ◽  
Type Iii Secretion ◽  
Yersinia Pseudotuberculosis ◽  
Bacterial Pathogen ◽  
Type Iii Secretion System ◽  
Inducible Promoter ◽  
Secretion System ◽  
Host Cells ◽  
Content Type ◽  
Type Iii

ABSTRACTYersinia pseudotuberculosisis a Gram-negative bacterial pathogen. Virulence inY. pseudotuberculosisrequires the plasmid-encoded Ysc type III secretion system (T3SS), which functions to translocate a set of effectors called Yops into infected host cells. The effectors function to antagonize phagocytosis (e.g., YopH) or to induce apoptosis (YopJ) in macrophages infected withY. pseudotuberculosis. Additionally, when antiphagocytosis is incomplete andY. pseudotuberculosisis internalized by macrophages, the bacterium can survive in phagosomes. Previous studies have shown that delivery of effectors into host cells occurs efficiently whenYersiniais extracellular. However, it is not clear whether the T3SS can be utilized by intracellularY. pseudotuberculosisto translocate Yops. This possibility was investigated here usingY. pseudotuberculosisstrains that express YopJ or YopH under the control of an inducible promoter. Bone marrow-derived murine macrophages were infected with these strains under conditions that prevented the survival of extracellular bacteria. Effector translocation was detected by measuring apoptosis or the activities of Yop-β-lactamase fusion proteins. Results showed that macrophages underwent apoptosis when YopJ expression was induced prior to phagocytosis, confirming that delivery of this effector prior to or during uptake is sufficient to cause cell death. However, macrophages also underwent apoptosis when YopJ was ectopically expressed after phagocytosis; furthermore, expression of the translocator YopB from intracellular bacteria also resulted in increased cell death. Analysis by microscopy showed that translocation of ectopically expressed YopH- or YopJ-β-lactamase fusions could be correlated with the presence of viableY. pseudotuberculosisin macrophages. Collectively, our results suggest that the Ysc T3SS ofY. pseudotuberculosiscan function within macrophage phagosomes to translocate Yops into the host cytosol.

Recent advances in mechanical properties of anisotropic conductive adhesive film for microelectronic packaging

2015 ◽  
Vol 27 (4) ◽  
pp. 164-177 ◽  
Author(s):  
Lilan Gao ◽  
Hong Gao ◽  
Xu Chen
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Stress Amplitude ◽  
Microelectronic Packaging ◽  
Mean Stress ◽  
Adhesive Film ◽  
Content Type ◽  
Hygrothermal Aging ◽  
Anisotropic Conductive Adhesive ◽  
The Impact

Purpose – This review paper aims to provide a better understanding of formulation and processing of anisotropic conductive adhesive film (ACF) material and to summarize the significant research and development work for the mechanical properties of ACF material and joints, which helps to the development and application of ACF joints with better reliability in microelectronic packaging systems. Design/methodology/approach – The ACF material was cured at high temperature of 190°C, and the cured ACF was tested by conducting the tensile experiments with uniaxial and cyclic loads. The ACF joint was obtained with process of pre-bonding and final bonding. The impact tests and shear tests of ACF joints were completed with different aging conditions such as high temperature, thermal cycling and hygrothermal aging. Findings – The cured ACF exhibited unique time-, temperature- and loading rate-dependent behaviors and a strong memory of loading history. Prior stress cycling with higher mean stress or stress amplitude restrained the ratcheting strain in subsequent cycling with lower mean stress or stress amplitude. The impact strength and adhesive strength of ACF joints increased with increase of bonding temperature, but they decreased with increase of environment temperature. The adhesive strength and life of ACF joints decreased with hygrothermal aging, whereas increased firstly and then decreased with thermal cycling. Originality/value – This study is to review the recent investigations on the mechanical properties of ACF material and joints in microelectronic packaging applications.

Parameter sensitivity analysis of stability of T-shaped rigid frame bridge by adopting swivel construction method

2020 ◽  
Vol 16 (5) ◽  
pp. 1203-1231
Author(s):  
Jiawei Wang ◽  
Quansheng sun
Keyword(s):  
Construction Method ◽  
Wind Effect ◽  
Construction Process ◽  
Change Rate ◽  
Content Type ◽  
Railway Traffic ◽  
Rigid Frame ◽  
The Stability ◽  
Wind Induced Vibration ◽  
The Impact

PurposeIn order not to affect the highway and railway traffic under the bridge during the construction process, bridges adopting swivel construction method are increasingly used at areas where the traffic is heavy. Previous studies are mostly conducted by assuming that the bridge is under its own stability conditions, without considering the impact of construction error, changes of external condition and wind-induced vibration on the stability of the bridge, which poses serious challenges to the bridge construction process. This paper aims to analyze the extent to which static load and fluctuating wind effect influence structural stability and to test the credibility of the structure.Design/methodology/approachA finite element calculation method is used to analyze a T-shaped rigid frame swivel bridge. A full bridge model was built, and a local model of the turntable structure established; the two are then combined means of node coupling. Subsequently, the three sensitivity indexes – deflection rate, stress change rate and the change rate of spherical hinges – are used to evaluate in what way the bridge stability is influenced under various factors.FindingsIt is found that the stability of the swivel bridge is quite sensitive to unilateral overweight, steel beam tension and wind-induced vibration effects but less sensitive to the change of bulk density. Also found is that the change of elastic modulus exerts some effects on deflection but has negligible effects on other stability indexes. Furthermore, the transverse unbalanced torque on the bridge generated by wind-induced vibration is an important factor in determining the size of the turntable, indicating that it is not just controlled by the weight of the bridge.Originality/valueAll factors affecting the stability of swivel construction are analyzed, and solutions to reduce the influence are proposed. The influence of wind-induced vibration effects on swivel construction is analyzed for the first time. It is pointed out that wind-induced vibration effects have great influence on the structure, and its influence could not be neglected.

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