bluuebunny/crossref_metadata_2025 huggingface dataset:
Roles of gender and basic need satisfaction in decent work perception and voice behavior
Authors: Huang Wenyuan , Shen Jie , Yuan Chuqin , Li Min
Published: August 2020

Purpose

How to foster voice behavior has always been a hot topic in organizational research; however, the mechanism through which performing decent work affects employee voice behavior remains to be fully understood. To address this deficiency, the current study investigates how basic need satisfaction may relate to perceived decent work and voice behavior and the moderating role of gender. Our research draws upon self-determination theory and social information processing theory.

Design/methodology/approach

The theoretical model was tested using two-wave investigation data collected from a sample of 349 employees and 85 supervisors in Southwest China.

Findings

Decent work perception was positively related to voice behavior, and this relationship was partially mediated by basic need satisfaction. In addition, the relationship between decent work perception and basic need satisfaction as well as the indirect effect of decent work perception on voice behavior via basic need satisfaction was stronger for men than for women.

Originality/value

This study highlights the pivotal roles of basic need satisfaction and gender in the consequences of decent work perception in the workplace. The authors provide new insights into the relationship between decent work perception and voice behavior and inspire scholars to elucidate other explanatory mechanisms in this link.
Students' perceptions regarding classroom attendance and its impact on their academic performance: evidence from a developing country
Authors: Almutawa Abdullah , Suwaidan Mishiel Said
Published: August 2020

Purpose

The purposes of this study are to identify the reasons that prevent students from attending lectures, to examine the impact of absenteeism on their academic performance and to explore the role of gender in their attendance.

Design/methodology/approach

A questionnaire survey made up of statements was distributed to accounting students. Descriptive measures, a five-point Likert scale, Pearson's chi-square test and phi test were employed to achieve the study's objectives.

Findings

The study shows that most of the accounting students surveyed are aware of the importance of attending lectures, since they believe that attendance will have a positive impact on their understanding of course material and on their academic performance. The study indicates that overall academic performance and student attendance are related. It also indicates that there is a statistically significant association between the overall academic performance of accounting students and their gender.

Practical implications

To gain greater insight into educators, academic institutes, researchers and parents concerning the reasons that lie behind students not attending accounting lectures in public higher education institutions in Kuwait and the effect of attendance on academic performance.

Originality/value

Most prior studies have been conducted in developed countries and Western contexts. Especially, with the potential perceived differences in cultures and norms, this empirical study is expected to contribute to fill the gap in this research field.
Do employability skills for business graduates meet the employers’ expectations? The case of retail Islamic banks of Bahrain
Authors: Al-Shehab Noor , AL-Hashimi Mukhtar , Madbouly Araby , Reyad Sameh , Hamdan Allam
Published: August 2020

Purpose

Managers claim that fresh graduates are unequipped to meet market demands. The aim of this study is to investigate the perception of employers in retail Islamic banks of Bahrain on newly graduated business students. The Singaporean Model of Employability Skills was implemented, to ascertain the mean ratings of employability skills in terms of their importance and the competency of business graduates.

Design/methodology/approach

This deductive research approach initiated with a literature review that identifies research gap and a model that was tested via a self-administration adopted survey by collected data from 220 senior employees at retail Islamic banks of Bahrain

Findings

The systematic of convenience sampling technique was used in selecting 161 samples and the researcher received only 85 completed questionnaire forms. Findings initiate that employers appreciated the importance of teamwork, risk management and decision-making skills. Their main recommendation was that employers should establish a durable bond with universities to enhance employability skills.

Originality/value

Because the researcher gathered all data from employers of different Islamic banks in Bahrain, this sector in addition will get the advantage of the results that banks will formulate their strategic plans accordingly to tackle the business graduates’ weaknesses. Likewise, universities and researchers might be motivated to look into new innovative methods that assist graduates to accommodate with market conditions.
Visualizing online collaborative writing strategies in higher education group assignments
Authors: Sundgren Marcus , Jaldemark Jimmy
Published: August 2020

Purpose

Working together in groups is a common and emphasized feature in today's society, and higher educational settings often utilize group assignments to enable students to develop collaborative skills. Therefore, the purpose of this article is to describe and analyze applied strategies and the patterns that emerge during students online collaborative writing in higher education group assignments. The research questions that this article aims to answer are (1) which patterns of students online collaborative writing emerge in higher education group assignments and (2) what strategies of online collaborative writing do higher education students apply in group assignments?

Design/methodology/approach

This study's design builds on Conversation Analysis to explore visualizations of Google Docs revision history of online collaborative writing documents. Documents from 25 student groups were the basis of the analysis. The visualizations used in this project are produced with the DocuViz Chrome extension.

Findings

The findings suggest that visualizations can provide a quick and fairly accurate estimate of collaborative strategies used when students write together online. Three patterns of document growth were identified, two of which could be directly linked to strategies for collaboration. Cramming patterns are indicative of low collaboration and concentrating patterns with high levels of collaboration.

Practical implications

The findings provide useful insight for teachers regarding the nature of collaboration taking place during online collaborative writing tasks. By visualizing the revision history, much can be learnt about the nature of the collaboration and of the individual group member's contributions in a student group that otherwise remains largely invisible to the teacher.

Originality/value

Prior studies have combined visualizations with extensive analysis of document content. This investigation shows that an examination of the visualization of the document's revision history can be used to draw conclusions about the nature of collaboration during the online writing process.
Impacts of procurement strategies on construction SMEs’ growth
Authors: Windapo Abimbola Olukemi , Olugboyega Oluseye , Odediran Sunday
Published: August 2020

Purpose

This study aims to investigate the impacts of procurement strategies on the growing proportion of construction small- and medium-sized enterprises (SMEs) and whether the size of the construction company moderates the effect.

Design/methodology/approach

This study adopted a quantitative research approach and a cross-sectional questionnaire survey in achieving its objectives. The survey requires the respondent to identify both the most successful and most outstanding project that the respondent was involved in between 2010 and 2016.

Findings

The study found that only traditional and management-oriented procurement strategies ensure the achievement of all growth plans for construction SMEs in South Africa; and that medium-sized construction enterprises achieve social growth such as community empowerment, managerial skills and advancement on the cidb Register of Contractors.

Practical implications

The findings of the study imply that policymakers should base their decisions regarding macroeconomic issues and growth plans for construction SMEs on the internal and external factors such as differences in the sizes of construction SMEs and differences in the suitability of procurement strategies affecting the growth of construction SMEs.

Originality/value

In past studies, the diversity amongst SMEs is often overlooked and SMEs are erroneously assumed to share similar objectives, possess equal capabilities and face challenges of the same magnitude. The original contribution of this study is shown in the investigation of the moderating effect of SMEs’ diversity (in terms of company size) on their growth proportion as influenced by procurement strategies.
Modeling and simulation of intersection quasi-moving block speed guidance based on connected vehicles
Authors: Xu Qing , Wang Jiangfeng , Wang Botong , Yan Xuedong
Published: August 2020

Purpose

This study aims to propose a speed guidance model of the CV environment to alleviate traffic congestion at intersections and improve traffic efficiency. By introducing the theory of moving block section for high-speed train control, a speed guidance model based on the quasi-moving block speed guidance (QMBSG) is proposed to direct platoon including human-driven vehicles and connected vehicles (CV) through the intersection coordinately.

Design/methodology/approach

In this model, the green time of the intersection is divided into multiple block intervals according to the minimal safety headway. Connected vehicles can pass through the intersection by following the block interval using the QMBSG model. The block interval is assigned dynamically according to the traveling relation of HV and CV, when entering the communication range of the intersection. To validate the comprehensive guidance effect of the proposed model, a general evaluation function (GEF) is established. Compared to CVs without speed guidance, the simulation results show that the GEF of QMBSG model has an obvious improvement.

Findings

Compared to CVs without speed guidance, the simulation results show that the GEF of QMBSG model has an obvious improvement. Also, compared to the single intersection speed guidance model, the GEF value of the QMBSG model improves over 17.1%. To further explore the guidance effect, the impact of sensitivity factors of the CVs’ environment, such as intersection environment, communication range and penetration rate (PR) is analyzed. When the PR reaches 75.0%, the GEF value will change suddenly and the model guidance effect will be significantly improved. This paper also analyzes the impact of the length of block interval under different PR and traffic demands. It is found that the proposed model has a better guidance effect when the length of the block section is 2 s, which facilitates traffic congestion alleviation of the intersection in practice.

Originality/value

Based on the aforementioned discussion, the contributions of this paper are three-fold. Based on the traveling information of HV/CV and the signal phase and timing plans, the QMBSG model is proposed to direct platoon consisting of HV and CV through the intersection coordinately, by following the block interval assigned dynamically. Considering comprehensively the indexes of mobility, safety and environment, a GEF is provided to evaluate the guidance effect of vehicles through the intersection. Sensitivity analysis is carried out on the QMBSG model. The key communication and traffic parameters of the CV environment are analyzed, such as path attenuation, PR, etc. Finally, the effect of the length of block interval is explored.
Sustaining Indigenous students' and families' well-being and culture in an Ontario school board
Authors: Washington Shaneé Adrienne
Published: August 2020

Purpose

This paper describes how an Ontario school board's majority First Nation, Metís and Inuit (FNMI) student population influenced the direction and priorities of the board toward culturally responsive and well-being focused initiatives. Using culturally sustaining/revitalizing pedagogy (CSRP) as a conceptual framework, it explores the board's efforts to meet the socioemotional and identity needs of its FNMI students (and families) through investments in professional learning communities (PLCs) and targeted programming and technologies.

Design/methodology/approach

This paper presents findings from one case in a larger multi-year (2015–2017), multiple-case (10 school boards) study by a university research team that included the author. Thematic analysis was used to code interviews and focus groups conducted with over 40 administrators, educators and community partners in the board featured in this paper.

Findings

The board's culturally responsive and well-being focused initiatives, while intended to support FNMI students' socioemotional success and sense of inclusiveness in schools, was inadequate at fostering and sustaining students' (and families') cultural survival and communal well-being.

Practical implications

Findings offer practical ways that schools serving large populations of FNMI students might support students' identity development and self-regulation skills in schools while also serving as a cautionary example of strategies that do not sufficiently address student challenges that are the result of ongoing legacies of colonization.

Originality/value

This study provides a distinctive example of a predominantly FNMI school board that, in recent years, has prioritized student well-being and identity development over achievement. It provides insight into the transformative possibilities and constraints of trying to support FNMI students' socioemotional healing and cultural sustenance in a colonized system.
Causal explanations for the evolution of ‘low gear’ locomotion in insular ruminants
Authors: Rozzi Roberto , Varela Sara , Bover Pere , Martin Jeff M.
Published: August 2020

Aim

Mammals on islands often undergo remarkable evolutionary changes. The acquisition of ‘low gear’ locomotion, namely short and robust limb elements, has been typically associated with the island syndrome in large mammals and, especially, ruminants. Here we provide an investigative framework to examine biotic and abiotic selective factors hypothesized to influence evolution of this peculiar type of gait.

Location

Islands worldwide.

Taxon

Bovidae.

Methods

We calculated response variables associated with ‘low gear’ locomotion in 21 extinct and extant insular bovids. We assembled data on the physiography of 11 islands and on life history and ecological traits of the focal taxa. We estimated 10 predictors (island area and four topographic indices, body mass, body size divergence, number of predators and competitors, large mammal richness) and used multiple regressions, regression trees, and random forests to assess their contextual importance.

Results

The acquisition of ‘low gear’ locomotion generally happens on islands with a small number of competitors. However, the roughness of the island terrain appears to be also important, without being a main driver. Finally, although the most extreme cases of ‘low gear’ locomotion occurred on islands with no mammalian predators, our models show a non‐significant relationship with this factor.

Main conclusions

The evolution of ‘low gear’ locomotion in insular ruminants does not simply result from phyletic dwarfing and predatory release. Variation in morphological responses within Bovidae to ecological and topographic traits suggests, instead, a complex interplay of biotic and abiotic factors. Current understanding on the main drivers of species evolutionary pathways and biogeographic patterns are disproportionally based on few taxa, mainly vertebrates, and in some extreme cases (like this one) even on few species. Here we show how adding more data, even within the same taxonomic group, can challenge historically accepted macroevolutionary and macroecological concepts.
Critical Europeans in an Age of Crisis: Irish and Portuguese Protesters' EU Perceptions
Authors: Moore Madelaine , Trommer Silke
Published: August 2020

This article examines Irish and Portuguese protesters' perceptions of the EU in the decade since the European debt crisis. Building on EU politics, social movement and protest literatures, we ask how domestic protesters in both countries perceive the EU during its age of crisis protest timescape. We find that critical Europeanism, which rejects technocratic and neoliberal Europe and works towards an alternative, social Europe, has travelled beyond austerity/bailout protests into women's rights and housing protests in both countries, although to varying degrees. We suggest that the expansion of critical European perceptions in these traditionally Europhile member states forms part of the social and political legacy of the European debt crisis, but also contributes to the continued Europeanization of the European social movement space. It could have positive impacts on the EU's legitimacy deficit if EU institutions engaged meaningfully with critical European voices.
Experimental Analysis of Salt Hydrate Latent Heat Thermal Energy Storage System With Porous Aluminum Fabric and Salt Hydrate as Phase Change Material With Enhanced Stability and Supercooling
Authors: Kumar Navin , Ness Ryan Von , Chavez Reynaldo , Banerjee Debjyoti , Muley Arun , Stoia Michael
Published: August 2020

Phase change materials (PCMs), especially salt hydrates possess high volumetric energy storage capacity in their transition temperature range. These materials are used in applications where it is necessary to store thermal energy due to temporary load shift between demand and availability. Thus, possible applications are HVAC, recovery of waste heat, and defense thermal management. Despite salt hydrates potential, the practical feasibility of latent heat storage with salt hydrates is limited due to low power rating, supercooling, phase segregation, and long-term stability. Its low power rating and long-term stability limits its application in most applications. This work experimentally validates the stability and thermal performance of a compact heat exchanger charged with salt hydrate during melting and freezing. The compact heat exchanger was designed with fins on both the heat transfer fluid (HTF) and salt hydrate PCM side. The thermal performance of the latent heat thermal energy storage system (LHTESS) was evaluated for various operating conditions. The results show that LHTESS could achieve an average heat transfer coefficient of 124 and 87 W/(m2 K) during melting and solidification, respectively. The stability of the system in suppressing supercooling was validated over 800 cycles with nucleating agent and active homogenous nucleation techniques. The supercooling was reduced to 3 °C with zinc hydroxyl nitrate as nucleating agent and less than 1 °C with the active homogenous nucleation technique. The LHTESS showed less than 6% degradation in energy storage capacity over 800 cycles.
Shock–Boundary Layer-Interaction Control Through Recirculation in a Hypersonic Inlet
Authors: Ruban Alex , Menezes Viren , Balasubramanian Sridhar , Srinivasan K.
Published: August 2020

This technical brief presents a flow separation mitigation device, called cavity-recirculator that can be used to control flow separation during shock wave–boundary layer interaction (SBLI) in high-speed intake flows. The cavity-recirculator isolates the flow separation bubble generated at the SBLI spot, thereby thinning the boundary layer and reducing the blockage of the inviscid stream in the duct. The device has a potential application in scramjet engine intakes/isolators. The cavity-recirculator was tested on a single-ramp-compression intake model in a hypersonic shock tunnel, in a freestream of Mach 8 (±0.1). The device operation and effectiveness were assessed by flow visualization and pressure measurements in the test model. The measurements and visualization displayed a mitigation of flow separation through an improved flow field with a single shock train and the absence of flow separation shock, in the inlet.
X-Ray Microtomography System Applied in Characterization of Lightweight Concrete Structures
Authors: Bastos Luan F. , de Araújo Olga M. O. , Machado Alessandra S. , Oliveira Davi F. , Lopes Ricardo T.
Published: August 2020

Microtomography is a powerful non-destructive method that allows the visualization of the internal structure of the object and makes possible to generate internal graphic models of the object. Concrete is a mixture widely used in the construction industry due to the union between its mechanical properties with the low cost for its production. The application of X-ray microtomography in lightweight concrete structures allows the visualization of the layout and formation of existing internal structures. In this work, it was possible to identify the presence of ethyl vinyl acetate (EVA) and piaçava fibers in the internal structure of the samples and to classify the high-density aggregates according to the ASTM C125-18 standard, as well as to evaluate the influence of the light aggregates in the increasing of the total porosity.
Seasonal trends and primary contributors to the low-frequency soundscape of the Cordell Bank National Marine Sanctuary
Authors: Haver Samara M. , Rand Zoe , Hatch Leila T. , Lipski Danielle , Dziak Robert P. , Gedamke Jason , Haxel Joseph , Heppell Scott A. , Jahncke Jaime , McKenna Megan F. , Mellinger David K. , Oestreich William K. , Roche Lauren , Ryan John , Van Parijs Sofie M.
Published: August 2020

Passive acoustic monitoring of ocean soundscapes can provide information on ecosystem status for those tasked with protecting marine resources. In 2015, the National Oceanic and Atmospheric Administration (NOAA) established a long-term, continuous, low-frequency (10 Hz–2 kHz) passive acoustic monitoring site in the Cordell Bank National Marine Sanctuary (CBNMS), located offshore of the central United States of America (U.S.) west coast, near San Francisco, CA. The California Current flows southward along the coast in this area, supporting a diverse community of marine animals, including several baleen whale species. Acoustic data analysis revealed that both large vessels and vocalizing baleen whales contribute to the ambient soundscape of the CBNMS. Sound levels fluctuated by month with the highest levels in the fall and lowest levels in the summer. Throughout the year, very low-frequency (10–100 Hz) sound levels were most variable. Vessels and whales overlap in their contributions to ambient sound levels within this range, although vessel contributions were more omnipresent, while seasonal peaks were associated with vocalizing whales. This characterization of low-frequency ambient sound levels in the CBNMS establishes initial baselines for an important component of this site's underwater soundscape. Standardized monitoring of soundscapes directly supports NOAA's ability to evaluate and report on conditions within national marine sanctuaries.
Temporal quantization deteriorates the discrimination of interaural time differences
Authors: Dieudonné Benjamin , Van Wilderode Mira , Francart Tom
Published: August 2020

Cochlear implants (CIs) often replace acoustic temporal fine structure by a fixed-rate pulse train. If the pulse timing is arbitrary (that is, not based on the phase information of the acoustic signal), temporal information is quantized by the pulse period. This temporal quantization is probably imperceptible with current clinical devices. However, it could result in large temporal jitter for strategies that aim to improve bilateral and bimodal CI users' perception of interaural time differences (ITDs), such as envelope enhancement. In an experiment with 16 normal-hearing listeners, it is shown that such jitter could deteriorate ITD perception for temporal quantization that corresponds to the often-used stimulation rate of 900 pulses per second (pps): the just-noticeable difference in ITD with quantization was 177 μs as compared to 129 μs without quantization. For smaller quantization step sizes, no significant deterioration of ITD perception was found. In conclusion, the binaural system can only average out the effect of temporal quantization to some extent, such that pulse timing should be well-considered. As this psychophysical procedure was somewhat unconventional, different procedural parameters were compared by simulating a number of commonly used two-down one-up adaptive procedures in Appendix B.
Looking for the light in Haiti
Authors: Bazell Robert
Published: August 2020

For physician Marie Marcelle Deschamps, COVID-19 is just the latest challenge.
Observation of small Fermi pockets protected by clean CuO
2
sheets of a high-
T
c
superconductor
Authors: Kunisada So , Isono Shunsuke , Kohama Yoshimitsu , Sakai Shiro , Bareille Cédric , Sakuragi Shunsuke , Noguchi Ryo , Kurokawa Kifu , Kuroda Kenta , Ishida Yukiaki , Adachi Shintaro , Sekine Ryotaro , Kim Timur K. , Cacho Cephise , Shin Shik , Tohyama Takami , Tokiwa Kazuyasu , Kondo Takeshi
Published: August 2020

An elusive pocket

Superconductivity in copper oxide materials emerges by doping a special kind of correlated state called the Mott insulator. However, studying what happens when a small concentration of charge carriers—holes or electrons—is added to a Mott insulator is experimentally challenging. It has been predicted that the so-called “Fermi pockets” should become visible during experimentation, but such pockets have not been unambiguously observed. Kunisada
et al.
studied the unusual cuprate Ba
2
Ca
4
Cu
5
O
10
(F,O)
2
, which has five copper oxide planes in a unit cell, whereas most cuprates have one or two (see the Perspective by Vishik). They observed two Fermi pockets in both photoemission and quantum oscillations data, with the innermost copper oxide planes playing a crucial role.

Science
, this issue p.
833
; see also p.
775
A coexistence that CuO
2
planes can see
Authors: Vishik Inna
Published: August 2020

Antiferromagnetism and superconductivity are not at odds in a quintuple-layer cuprate
The importins of pain
Authors: Yousuf Muhammad Saad , Price Theodore J.
Published: August 2020

A nuclear protein importer modulates gene expression to control the persistence of neuropathic pain
Vaccine nationalism's politics
Authors: Fidler David P.
Published: August 2020

Before coronavirus disease 2019 (COVID-19) struck, cooperation on global health—especially for pandemic preparedness and response—would, we told ourselves, enhance national security, support economic wealth, protect human rights, and facilitate humanitarian assistance around the world. However, the politics of the coronavirus catastrophe do not reflect such national interests or international solidarity. “Vaccine nationalism” is more evidence that efforts to elevate health cooperation—and the sciences that inform it—have produced more rhetoric than political roots within countries and the international community.
The Interactive Effects of Crude Oil and Corexit 9500 on Their Biodegradation in Arctic Seawater
Authors: Gofstein Taylor R. , Perkins Matthew , Field Jennifer , Leigh Mary Beth
Published: August 2020

Chemical dispersants such as Corexit 9500 are commonly used in oil spill response and are currently under consideration for use in the Arctic, where their fate and effects have not been well studied. This research was performed to determine the interactive effects of the copresence of crude oil and Corexit 9500 on the degradation of components from each mixture and the associated microbial community structure over time in Arctic seawater. These findings will help yield a better understanding of the biodegradability of dispersant components applied to an oil spill, the temporal microbial community response to dispersed oil, and the fundamental microbial ecology of organic contaminant biodegradation processes in the Arctic marine environment.
Competition and Caries on Enamel of a Dual-Species Biofilm Model with Streptococcus mutans and Streptococcus sanguinis
Authors: Díaz-Garrido Natalia , Lozano Carla P. , Kreth Jens , Giacaman Rodrigo A.
Published: August 2020

The concept of caries as an ecological disease implies the understanding of the intricate relationships among the populating microorganisms. Under frequent sugar exposure, some bacteria from the dental biofilm develop pathogenic traits that lead to imbalances (dysbiosis). Depending on which microorganism colonizes the dental surface first, different competition strategies may be developed. Studying the interactions in the entire dental biofilm is not an easy task. In this study, therefore, we modeled the interplay among these microorganisms using a caries-inducing species (
S. mutans
) and a health-associated species (
S. sanguinis
). Initial enamel adherence with
S. sanguinis
seems to induce more intense competition against typically caries-inducing species. Besides continuous exposure with sugars, early colonization of the enamel by highly cariogenic species like
S. mutans
appears to be needed to develop caries lesions as well. Promoting early colonization by health-associated bacteria such as
S. sanguinis
could help to maintain oral health, delaying dysbiosis.
Molecular Structure and Functional Analysis of Pyocin S8 from Pseudomonas aeruginosa Reveals the Essential Requirement of a Glutamate Residue in the H-N-H Motif for DNase Activity
Authors: Turano Helena , Gomes Fernando , Domingos Renato M. , Degenhardt Maximilia F. S. , Oliveira Cristiano L. P. , Garratt Richard C. , Lincopan Nilton , Netto Luis E. S.
Published: August 2020

Multidrug resistance (MDR) is a serious threat to public health, making the development of new antimicrobials an urgent necessity. Pyocins are protein antibiotics produced by Pseudomonas aeruginosa strains to kill closely related cells during intraspecific competition. Here, we report an in-depth biochemical, microbicidal, and structural characterization of a new S-type pyocin, named S8. Initially, we described the domain organization and secondary structure of S8. Subsequently, we observed that a recombinant S8 composed of the killing subunit in complex with the immunity (ImS8) protein killed the strain PAO1. Furthermore, mutation of a highly conserved glutamic acid to alanine (Glu100Ala) completely inhibited this antimicrobial activity. The integrity of the H-N-H motif is probably essential in the killing activity of S8, as Glu100 is a highly conserved residue of this motif. Next, we observed that S8 is a metal-dependent endonuclease, as EDTA treatment abolished its ability to cleave supercoiled pUC18 plasmid. Supplementation of apo S8 with Ni2+ strongly induced this DNase activity, whereas Mn2+ and Mg2+ exhibited moderate effects and Zn2+ was inhibitory. Additionally, S8 bound Zn2+ with a higher affinity than Ni2+ and the Glu100Ala mutation decreased the affinity of S8 for these metals, as shown by isothermal titration calorimetry (ITC). Finally, we describe the crystal structure of the Glu100Ala S8 DNase-ImS8 complex at 1.38 Å, which gave us new insights into the endonuclease activity of S8. Our results reinforce the possibility of using pyocin S8 as an alternative therapy for infections caused by MDR strains, while leaving commensal human microbiota intact.

IMPORTANCE Pyocins are proteins produced by Pseudomonas aeruginosa strains that participate in intraspecific competition and host-pathogen interactions. They were first described in the 1950s and since then have gained attention as possible new antibiotics. However, there is still only scarce information about the molecular mechanisms by which these molecules induce cell death. Here, we show that the metal-dependent endonuclease activity of pyocin S8 is involved with its antimicrobial action against strain PAO1. We also describe that this killing activity is dependent on a conserved Glu residue within the H-N-H motif. The potency and selectivity of pyocin S8 toward a narrow spectrum of P. aeruginosa strains make this protein an attractive antimicrobial alternative for combatting MDR strains, while leaving commensal human microbiota intact.
Functions of the BamBCDE Lipoproteins Revealed by Bypass Mutations in BamA
Authors: Hart Elizabeth M. , Silhavy Thomas J.
Published: August 2020

The heteropentomeric β-barrel assembly machine (BAM complex) is responsible for folding and inserting a diverse array of β-barrel outer membrane proteins (OMPs) into the outer membrane (OM) of Gram-negative bacteria. The BAM complex contains two essential proteins, the β-barrel OMP BamA and a lipoprotein BamD, whereas the auxiliary lipoproteins BamBCE are individually nonessential. Here, we identify and characterize three bamA mutations, the E-to-K change at position 470 (bamAE470K), the A-to-P change at position 496 (bamAA496P), and the A-to-S change at position 499 (bamAA499S), that suppress the otherwise lethal ΔbamD, ΔbamB ΔbamC ΔbamE, and ΔbamC ΔbamD ΔbamE mutations. The viability of cells lacking different combinations of BAM complex lipoproteins provides the opportunity to examine the role of the individual proteins in OMP assembly. Results show that, in wild-type cells, BamBCE share a redundant function; at least one of these lipoproteins must be present to allow BamD to coordinate productively with BamA. Besides BamA regulation, BamD shares an additional essential function that is redundant with a second function of BamB. Remarkably, bamAE470K suppresses both, allowing the construction of a BAM complex composed solely of BamAE470K that is able to assemble OMPs in the absence of BamBCDE. This work demonstrates that the BAM complex lipoproteins do not participate in the catalytic folding of OMP substrates but rather function to increase the efficiency of the assembly process by coordinating and regulating the assembly of diverse OMP substrates.

IMPORTANCE The folding and insertion of β-barrel outer membrane proteins (OMPs) are conserved processes in mitochondria, chloroplasts, and Gram-negative bacteria. In Gram-negative bacteria, OMPs are assembled into the outer membrane (OM) by the heteropentomeric β-barrel assembly machine (BAM complex). In this study, we probe the function of the individual BAM proteins and how they coordinate assembly of a diverse family of OMPs. Furthermore, we identify a gain-of-function bamA mutant capable of assembling OMPs independently of all four other BAM proteins. This work advances our understanding of OMP assembly and sheds light on how this process is distinct in Gram-negative bacteria.
Severe Human Lassa Fever Is Characterized by Nonspecific T-Cell Activation and Lymphocyte Homing to Inflamed Tissues
Authors: Port Julia R. , Wozniak David M. , Oestereich Lisa , Pallasch Elisa , Becker-Ziaja Beate , Müller Jonas , Rottstegge Monika , Olal Catherine , Gómez-Medina Sergio , Oyakhliome Jennifer , Ighodalo Yemisi , Omomoh Emmanuel , Olokor Thomas , Adomeh Donatus I. , Asogun Danny , Ogbani-Emovon Ephraim , Hartmann Kristin , Krasemann Susanne , Nelson Emily V. , Escudero-Pérez Beatriz , McElroy Anita K. , Günther Stephan , Muñoz-Fontela César
Published: August 2020

Lassa fever may cause severe disease in humans, in particular in areas of endemicity like Sierra Leone and Nigeria. Despite its public health importance, the pathophysiology of Lassa fever in humans is poorly understood. Here, we present clinical immunology data obtained in the field during the 2018 Lassa fever outbreak in Nigeria indicating that severe Lassa fever is associated with activation of T cells antigenically unrelated to Lassa virus and poor Lassa virus-specific effector T-cell responses. Mechanistically, we show that these bystander T cells express defined tissue homing signatures that suggest their recruitment to inflamed tissues and a putative role of these T cells in immunopathology. These findings open a window of opportunity to consider T-cell targeting as a potential postexposure therapeutic strategy against severe Lassa fever, a hypothesis that could be tested in relevant animal models, such as nonhuman primates.
The Golgi Calcium ATPase Pump Plays an Essential Role in Adeno-associated Virus Trafficking and Transduction
Authors: Madigan Victoria J. , Berry Garrett E. , Tyson Tyne O. , Nardone-White Dasean , Ark Jonathan , Elmore Zachary C. , Murlidharan Giridhar , Vincent Heather A. , Asokan Aravind
Published: August 2020

Adeno-associated viruses (AAVs) have proven to be effective gene transfer vectors. However, our understanding of how the host cell environment influences AAV transduction is still evolving. In the present study, we investigated the role of
ATP2C1
, which encodes a membrane calcium transport pump, SPCA1, essential for maintaining cellular calcium homeostasis on AAV transduction. Our results indicate that cellular calcium is essential for efficient intracellular trafficking and conformational changes in the AAV capsid that support efficient genome transcription. Further, we show that pharmacological modulation of cellular calcium levels can potentially be applied to improve the AAV gene transfer efficiency.
Natural Variation in Clinical Isolates of Candida albicans Modulates Neutrophil Responses
Authors: Shankar Madhu , Lo Tricia L. , Traven Ana
Published: August 2020

Neutrophils are the key immune cell type for host defenses against infections with
Candida albicans
.
C. albicans
strains isolated from patients display large phenotypic diversity, but how this diversity impacts host-pathogen interactions with neutrophils is incompletely defined. Here, we show that important neutrophil responses, such as accumulation of reactive oxygen species and neutrophil extracellular traps, as well as the levels of phagocytosis and killing of the pathogen, differ when comparing diverse
C. albicans
isolates. A bloodstream patient isolate previously described as more suited to commensalism than pathogenesis in animal models is relatively “silent” to neutrophils and resistant to killing. Our findings illuminate the relationships between fungal morphogenesis, neutrophil responses, and
C. albicans
survival. Our findings suggest that host phenotypes of a commensally adapted strain could be driven by resistance to immune clearance and indicate that we should extend our studies beyond the “prototype” strain SC5314 for deeper understanding of
Candida
-neutrophil interactions.
Novel Method for the Separation of Male and Female Gametocytes of the Malaria Parasite
Plasmodium falciparum
That Enables Biological and Drug Discovery
Authors: Ridgway Melanie C. , Shea Kwong Sum , Cihalova Daniela , Maier Alexander G.
Published: August 2020

The protozoan
Plasmodium falciparum
causes the most severe form of human malaria. The development of sexual forms (so-called gametocytes) is crucial for disease transmission. However, knowledge of these forms is severely hampered by the paucity of sex-specific markers and the inability to extract single sex gametocytes in high purity. Moreover, the identification of compounds that specifically affect one sex is difficult due to the female bias of the gametocytes. We have developed a system that allows for the separation of male and female gametocytes from the same population. Applying our system, we show that male and female parasites mature at different rates, which might have implications for transmission. We also identified new sex-specific genes that can be used as sex markers or to unravel sex-specific functions. Our system will not only aid in the discovery of much needed gametocidal compounds, but it also represents a valuable tool for exploring malaria transmission biology.
Multimodal imaging and adaptive optics in internal limiting membrane dystrophy
Authors: Oli Avadhesh , Balakrishnan Divya
Published: August 2020

An 18-year-old boy presented with a mild blurring of vision in both his eyes for the last 2 years. His best-corrected visual acuity was 20/60 in both the eyes with normal colour vision. Fundus evaluation showed exaggerated shiny reflex from the internal limiting membrane (ILM) with the wrinkled inner retinal surface at posterior pole. No vessel attenuation or retinal pigment epithelium changes were evident. Optical coherence tomography showed thickened ILM, which was appreciated in fundus photo also. The electrodiagnostic tests were normal, and the photoreceptors appeared normal in adaptive optics in the central macula at 2°–4° eccentricity. Among the very few reported cases of Muller cells sheen dystrophy, our patient was the probably the youngest and was picked up by a thoughtful ophthalmologist in detailed clinical examination. Adaptive optics in the case of ILM dystrophy is also not reported earlier.
Falciform ligament appendagitis after Roux-en-Y bypass surgery mimicking acute cholecystitis
Authors: Rousslang Lee K , McCoy McHuy F , Gould C Frank
Published: August 2020

Fatty falciform ligament appendage torsion (F-FLAT) is a rare type of intraperitoneal focal fat infarction that involves torsion of a fatty appendage of the falciform ligament. It may cause severe pain, mimicking an acute abdomen, but is typically self-limited and does not require hospitalisation or surgery. As a type of intraperitoneal focal fat infarction, it shares many of the same physiological, clinical and radiological features of epiploic appendagitis. To our knowledge, F-FLAT has not previously been reported in a patient following a laparoscopic Roux-en-Y gastric bypass surgery. Identifying falciform ligament appendagitis is critical because it can prevent unnecessary hospitalisation, follow-up studies and surgery.
Self-management interventions to reduce healthcare use and improve quality of life among patients with asthma: systematic review and network meta-analysis
Authors: Hodkinson Alexander , Bower Peter , Grigoroglou Christos , Zghebi Salwa S , Pinnock Hilary , Kontopantelis Evangelos , Panagioti Maria
Published: August 2020

Objective

To compare the different self-management models (multidisciplinary case management, regularly supported self-management, and minimally supported self-management) and self-monitoring models against usual care and education to determine which are most effective at reducing healthcare use and improving quality of life in asthma.

Design

Systematic review and network meta-analysis.

Data sources

Medline, the Cochrane Library, CINAHL, EconLit, Embase, Health Economics Evaluations Database, NHS Economic Evaluation Database, PsycINFO, and ClinicalTrials.gov from January 2000 to April 2019.

Review methods

Randomised controlled trials involving the different self-management models for asthma were included. The primary outcomes were healthcare use (hospital admission or emergency visit) and quality of life. Summary standardised mean differences (SMDs) and 95% credible intervals were estimated using bayesian network meta-analysis with random effects. Heterogeneity and publication bias were assessed.

Results

From 1178 citations, 105 trials comprising 27 767 participants were included. In terms of healthcare use, both multidisciplinary case management (SMD –0.18, 95% credible interval −0.32 to −0.05) and regularly supported self-management (–0.30, −0.46 to −0.15) were significantly better than usual care. For quality of life, only regularly supported self-management (SMD 0.54, 0.11 to 0.96) showed a statistically significant benefit compared with usual care. For trials including adolescents/children (age 5-18 years), only regularly supported self-management showed statistically significant benefits (healthcare use: SMD –0.21, −0.40 to −0.03; quality of life: 0.23, 0.03 to 0.48). Multidisciplinary case management (SMD –0.32, −0.50 to −0.16) and regularly supported self-management (–0.32, −0.53 to −0.11) were most effective at reducing healthcare use in patients with symptoms of severe asthma at baseline.

Conclusions

This network meta-analysis indicates that regularly supported self-management reduces the use of healthcare resources and improves quality of life across all levels of asthma severity. Future healthcare investments should provide support that offer reviews totalling at least two hours to establish self-management skills, reserving multidisciplinary case management for patients with complex disease.

Systematic review registration

PROSPERO number CRD42019121350.
Increasing metformin concentrations and its excretion in both rat and porcine ex vivo normothermic kidney perfusion model
Authors: Posma Rene A , Venema Leonie H , Huijink Tobias M , Westerkamp Andrie C , Wessels A Mireille A , De Vries Nynke J , Doesburg Frank , Roggeveld J , Ottens Petra J , Touw Daan J , Nijsten Maarten W , Leuvenink Henri G D
Published: August 2020

Introduction

Metformin can accumulate and cause lactic acidosis in patients with renal insufficiency. Metformin is known to inhibit mitochondria, while renal secretion of the drug by proximal tubules indirectly requires energy. We investigated whether addition of metformin before or during ex vivo isolated normothermic machine perfusion (NMP) of porcine and rat kidneys affects its elimination.

Research design and methods

First, Lewis rats were pretreated with metformin or saline the day before nephrectomy. Subsequently, NMP of the kidney was performed for 90 min. Metformin was added to the perfusion fluid in one of three different concentrations (none, 30 mg/L or 300 mg/L). Second, metformin was added in increasing doses to the perfusion fluid during 4 hours of NMP of porcine kidneys. Metformin concentration was determined in the perfusion fluid and urine by liquid chromatography-tandem mass spectrometry.

Results

Metformin clearance was approximately 4–5 times higher than creatinine clearance in both models, underscoring secretion of the drug. Metformin clearance at the end of NMP in rat kidneys perfused with 30 mg/L was lower than in metformin pretreated rats without the addition of metformin during perfusion (both p≤0.05), but kidneys perfused with 300 mg/L trended toward lower metformin clearance (p=0.06). Creatinine clearance was not different between treatment groups. During NMP of porcine kidneys, metformin clearance peaked at 90 min of NMP (18.2±13.7 mL/min/100 g). Thereafter, metformin clearance declined, while creatinine clearance remained stable. This observation can be explained by saturation of metformin transporters with a Michaelis-Menten constant (95% CI) of 23.0 (10.0 to 52.3) mg/L.

Conclusions

Metformin was secreted during NMP of both rat and porcine kidneys. Excretion of metformin decreased under increasing concentrations of metformin, which might be explained by saturation of metformin transporters rather than a self-inhibitory effect. It remains unknown whether a self-inhibitory effect contributes to metformin accumulation in humans with longer exposure times.