bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of engine oil additives reduction on the tribofilm structure of a cylinder liner model surface
Authors: Miranda-Medina Maria de Lourdes , Tomastik Christian , Truglas Tia , Groiss Heiko , Jech Martin
Published: August 2019

Purpose

The purpose of this paper is to provide a general picture for describing the formed tribofilm, including chemical and physical aspects in the micro-scale and the nano-scale. In a previous study, the durability of zinc dialkyl dithiophosphate (ZDDP) tribofilms on cylinder liner samples has been investigated in a tribometer model system by using fresh and aged fully formulated oils and replacing them with PAO8 without additives. Analyses of the derived tribofilms by means of X-ray photoelectron spectroscopy and scanning electron microscopy could give some hints about the underlying mechanisms of the tribofilm build-up and wear performance, but a final model has not been achieved.

Design/methodology/approach

Thus, characterisation of these tribofilms by means of focused ion beam-transmission electron microscopy (FIB-TEM) and energy dispersive X-ray spectroscopy is presented and a concluding model of the underlying mechanisms of tribofilm build-up is discussed in this paper.

Findings

For tribotests running first with fresh fully formulated engine oil, a rather homogeneous ZDDP-like tribofilm is found underneath a carbon rich tribofilm after changing to non-additivated PAO8. However, when the tests run first with aged fully formulated engine oil, no ZDDP-like tribofilm has been found after changing to non-additivated PAO8, but a wear protective carbon rich tribofilm.

Originality/value

The obtained results provide insights into the structure and durability of tribofilms. Carbon-based tribofilms are built up on the basis of non-additivated PAO8 because of the previously present ZDDP tribofilms, which suggests an alternative way to reducing the consumption of antiwear additives.
Effect of cage dynamic unbalance on the cage’s dynamic characteristics in high-speed cylindrical roller bearings
Authors: Cui Yongcun , Deng Sier , Yang Haisheng , Zhang Wenhu , Niu Rongjun
Published: August 2019

Purpose

The purpose of this paper is to study the influence of the cage dynamic unbalance on the dynamic performances in cylindrical roller bearings.

Design/methodology/approach

The dynamic analysis model which considering cage dynamic unbalance is presented, and the relationship between the cage dynamic unbalance and the cage stability, the cage slip ratio and the cage skew angle is investigated.

Findings

Cage dynamic unbalance has a great effect on the cage stability. The cage dynamic unbalance which in an axial excursion affects the cage characteristics is greater than that only in the radial direction. The cage slip ratio and the cage skew increases with the cage dynamic unbalance, especially with the axial excursion. The non-metal cage is more sensitive to the cage dynamic unbalance than that of the metal cage.

Originality/value

The analytical method and model can be applied by the bearing engineering designers.
Winning engaged consumers
Authors: Bazi Saleh , Hajli Alireza , Hajli Nick , Shanmugam Mohana , Lin Xiaolin
Published: August 2019

Purpose

Under the sunlight of social commerce, few concepts have blossomed like value co-creation. But when blurred strategies are implemented, the opportunity to wilt a brand is high. To avoid the miscues and the controversies, an ascendant step is to engage consumers with social commerce sites. The purpose of this paper is to propose three antecedents to engage consumers with social commerce sites, namely, social support, social commerce value and social commerce information sharing, and the effect of brand engagement on the intention of brand co-creation.

Design/methodology/approach

This study used survey data from 234 Iranians with experience using social commerce sites. Variance-based structural equation modeling using the partial least squares path modeling approach was adopted to analyze the structural model.

Findings

The authors found that social support, social commerce value and social commerce information sharing positively foster brand engagement. The study also revealed that brand engagement is a significant predictor of brand co-creation intention.

Originality/value

The study is the first study that considers and explains brand engagement from social support theory, social commerce value theory and social commerce information exchange. Also, the study shows how consumers can be an integral part of a brand. Unlike other studies which were done in industrialized countries, this study was employed in Iran.
Entrepreneurial learning; intuiting, scanning, internalizing and routinizing
Authors: Breslin Dermot
Published: August 2019

Purpose

Despite an increasing number of publications focusing on the phenomenon of entrepreneurial learning, it is still unclear how this learning process differs from wider organizational learning. This paper aims to address this gap by highlighting four key processual dimensions unique to entrepreneurial learning: intuiting, scanning, internalizing and routinizing.

Design/methodology/approach

Drawing on various conceptual and empirical papers published in this area over the past 20 years, common threads in the literature are identified, which point towards these four key dimensions of entrepreneurial learning.

Findings

It is thus argued that the ability of the entrepreneurial team to learn form and adapt to changes in the external market involves all four dimensions of intuiting, scanning, internalizing and routinizing. Intuiting involves drawing on prior knowledge to create new opportunity sets, and skills. These ideas and skills are then tested in the market, through scanning and market research. Internalizing allows the entrepreneurial team to question taken for granted assumptions, as existing ways of working and views of the world are continually adapted. Finally, routinization is the process whereby the entrepreneurial team accumulates a situated knowledge of the changing world around them, and in the process, frees up valuable cognitive resources, needed in the continual process of intuiting, scanning and internalizing.

Originality/value

It is argued that the adaptability of entrepreneurial ventures hinges on all four processual dimensions.
Ozone will remain a threat for plants independently of nitrogen load
Authors: Feng Zhaozhong , Shang Bo , Li Zhengzhen , Calatayud Vicent , Agathokleous Evgenios
Published: August 2019

Elevated concentrations of ground‐level ozone (O3) and atmospheric nitrogen (N) deposition occur concurrently. The negative effects of elevated O3 on plants have been widely studied and are well understood nowadays. However, how the effects of elevated O3 on plants may be driven by N deposition remains an unsolved puzzle.

We conducted a meta‐analysis and showed that the negative effects of elevated O3 on photosynthesis, stomatal conductance, growth and biomass production of semi‐natural and natural vegetation may remain unchanged by N deposition in the coming future under realistic increases in O3 concentrations (+20 to 40 ppb) and N deposition (up to 60 kg ha−1 year−1). The negative effect of elevated O3 on chlorophyll content is offset by soil N addition; however, the negative effect on biomasses is not offset by soil N addition.

Across functional groups and O3 levels, N addition exacerbated O3 effects on root when N increased from 0–10 kg N ha−1 year−1 to 11–30 kg N ha−1 year−1. However, an analysis as per the plant functional group revealed that such a N‐dependent O3 effect was significant only in perennial non‐woody plants, and was non‐significant when only realistic increases in O3 concentrations were considered. Likewise, N addition appeared to exacerbate O3‐negative effects on photosynthesis of trees when N increased from 0–30 kg N ha−1 year−1 to >60 kg N ha−1 year−1; however, this effect was significant only when realistic increases in O3 concentrations were considered.

The results suggest potential error in the current estimates of the overall O3 impacts on plants due to no consideration of soil N availability, and encourage further studies on the interaction of O3 and N availability that will permit more robust analyses in the future. Elevated O3 will likely remain a persistent agricultural and ecological issue independently of N deposition.

A free Plain Language Summary can be found within the Supporting Information of this article.
Prescription drug monitoring programs: Assessing the association between “best practices” and opioid use in Medicare
Authors: Moyo Patience , Simoni‐Wastila Linda , Griffin Beth Ann , Harrington Donna , Alexander G. Caleb , Palumbo Francis , Onukwugha Eberechukwu
Published: August 2019

Objective

To estimate the impact of implementing prescription drug monitoring program (PDMP) best practices on prescription opioid use.

Data Sources

2007–2012 Medicare claims for noncancer pain patients, and PDMP attributes from the Prescription Drug Abuse Policy System.

Study Design

We derived PDMP composite scores using the number of best practices adopted by states (range: 0‐14), classifying states as either no PDMP, low strength (0 < score < median), or high strength (score ≥ median). Using generalized linear models, we quantified the association between the PDMP score category and opioid use measures—overall and stratified by disability/age. Sensitivity analyses assessed the general Medicare sample regardless of pain diagnoses, individual PDMP characteristics, and compared GEE model findings to models with state fixed effects.

Principal Findings

Compared to non‐PDMP states, strong PDMP states had lower opioid cumulative doses (−296 mg; 95% CI: −512, −132), days supplied (−7.84; 95% CI: −10.6, −5.04), prescription fill rates (0.97; 95% CI: 0.95, 0.98), and mean daily doses (−2.31 mg; 95% CI: −3.14, −1.48) but greater prevalence of high opioid doses in disabled adults, whereas there was little or no change in older adults. Findings in states with weak PDMPs were substantively similar to those of strong PDMPs. Results from sensitivity analyses were mostly consistent with main findings except there was a null relationship with mean daily doses and high doses in models with state fixed effects.

Conclusions

Comprehensive or minimal adoption of PDMP best practices was associated with mostly comparable effects on Medicare beneficiaries’ opioid use; however, these effects were concentrated among nonelderly disabled adults.
Association between insulin and post‐caesarean resuscitation rates in infants of women with GDM: A retrospective study
Authors: Ng Aloysius , Liu Anthony , Nanan Ralph
Published: August 2019

Background

Gestational diabetes mellitus (GDM) and caesarean deliveries independently increase the risk of postoperative complications. There are limited data on the influence of insulin use on the outcomes of neonates who were delivered via caesarean section. We sought to investigate the impact of insulin use in women with GDM on resuscitation rates of infants post caesarean delivery.

Methods

A retrospective database review of women with singleton term (≥ 37 weeks) pregnancies who were on insulin for GDM delivering between January 2005 and December 2014 at a major metropolitan hospital in Sydney.

Results

One thousand eight hundred and fifty‐seven women with GDM were identified. The mean age was 31.01 ± 5.63 years and mean gestational period of 39.07 ± 1.00 weeks. 31.0% received insulin treatment for GDM. Women who were on insulin were older (31.9 ± 5.7 vs 30.6 ± 5.6 years, P < 0.001), had a higher body mass index (BMI) (31.2 ± 7.7 vs 29.0 ± 7.4 kg/m2, P < 0.001), higher rates of preeclampsia (7.3% vs 4.1%, P = 0.004), lower rates of alcohol consumption (0.4% vs 1.7%, P = 0.014), and had infants with lower resuscitation rates (21.2% vs 28.6%, P = 0.001). Infants who required resuscitation had a lower gestational age, lower five‐minute APGAR score, and lower birth weight, length, and head circumferences. On multivariate analysis, women with GDM treated with insulin (odds ratio [OR] = 0.69, CI = 0.54‐0.89, P = 0.004), higher gestational age (OR = 0.88, CI = 0.78‐0.99, P = 0.032), higher maternal BMI (OR = 1.02, CI = 1.01‐1.04, P = 0.005), and emergency caesarean (OR = 2.33, CI = 1.74‐3.12, P < 0.001) independently predicted incidence of resuscitation.

Conclusions

The findings suggest a relationship between insulin use and reduced resuscitation rates of infants born from mothers with GDM. Further studies investigating the role, dosage, and criteria for insulin use in women with GDM are required.
Sampling and analysis frameworks for inference in ecology
Authors: Williams Byron K. , Brown Eleanor D.
Published: August 2019

Reliable statistical inference is central to ecological research, much of which seeks to estimate population attributes and their interactions. The issue of sampling design and its relationship to inference has become increasingly important due to rapid proliferation of modelling methodology (line transect modelling, capture‐recapture, estimation of occurrence, model selection procedures, hierarchical modelling) and new sampling approaches (adaptive sampling, other specialized designs). It is important for ecologists using these advanced methods to be aware of how the linkages between sample selection and data analysis can potentially affect inference.

We examine design‐based and model‐based inference frameworks for ecological data collected randomly, purposively or opportunistically. We elucidate differences in the probability structures for data arising from these frameworks, clarify the assumptions that underlie them, and demonstrate their differences.

Design based inference builds on a probability structure inherited from randomized data collection, whereas model‐based inference relies on an assumed stochastic model of the data. By itself, a design‐based approach is of limited value for inferences about causal hypotheses. In contrast, model‐based inference is dependent on a conditionality principle that can seldom be shown to be met for an ecological system. We describe the conditions under which one can safely ignore sampling design in model‐based analysis, along with inferential implications if these conditions are not met. The special case of opportunistic sampling is discussed.

We present a combined framework that takes advantage of both approaches to inference, and provides a robust methodology that can deal with the modelling of sampling problems such as non‐detection and misclassification, as well as the exploration of causal hypotheses. The combined framework can be useful for identifying optimal sampling strategies.

Each approach to inference has its strengths and weaknesses, and practitioners should be aware of these in order to tailor designs and analyses to specific questions. We use the approaches and their underlying rationales to provide guidelines for choosing designs and estimators for reliable inference.
Managerial characteristics and stock market investment: evidence from China
Authors: Yang Jingjing , Xin Yuan , Jun Xiao
Published: August 2019

We examine the effect of managerial characteristics on investment in the stock market by listed firms in China. Our empirical findings suggest that higher levels of cash‐based compensation may increase both the propensity of investing in the stock market and the total amount of investment. On the other hand, managerial holdings discourage managers from investing in stock markets and also lead to a decrease in the amount of investment. This study sheds light on managerial risk‐taking incentives. Moreover, this study fills the gap in the literature by providing evidence for the determinants of listed firms’ stock market investment.
Regional changes in ∆FosB expression in rat brain following MDMA self‐administration predict increased sensitivity to effects of locally infused MDMA
Authors: van de Wetering Ross , Schenk Susan
Published: August 2019

Repeated exposure to drugs produces a plethora of persistent brain changes, some of which underlie the development of drug addiction. An important objective of addiction research is to identify the brain changes that might mediate the transition from drug use to drug misuse. The persistent accumulation of the transcription factor, ∆FosB, following repeated drug exposure provides a means of achieving this objective. Experiments were conducted on sexually mature male Sprague‐Dawley rats. The effects of extensive 3,4‐methylenedioxymethamphetamine (MDMA) self‐administration on immunohistochemical measurements of ∆FosB accumulation in 12 brain regions was compared with a matched, drug‐naive, control group. Other groups were pretreated with MDMA (0.0 or 10.0 mg/kg, ip, once daily for 5 days), and the locomotor‐activating effect of MDMA (200 μg/side) microinjected bilaterally into brain regions selected on the basis of the ∆FosB results was subsequently determined. MDMA self‐administration significantly increased ∆FosB expression in the nucleus accumbens core, ventromedial and dorsomedial caudate‐putamen, anterior cingulate, prelimbic, infralimbic, and orbitofrontal cortex, and both the central and basolateral amygdala, but not in the ventrolateral or dorsolateral caudate‐putamen. Increases in the nucleus accumbens shell were substantial but were not significant following statistical correction for multiple comparisons. MDMA pretreatment enhanced MDMA‐produced hyperactivity only when administered into the nucleus accumbens or the medial, but not the lateral, caudate‐putamen, mirroring the ∆FosB results. These data compare favorably to results following repeated exposure to other drugs of abuse and support the idea of common neuroplastic changes following repeated drug exposure.
Dysregulation of the histone demethylase KDM6B in alcohol dependence is associated with epigenetic regulation of inflammatory signaling pathways
Authors: Johnstone Andrea L. , Andrade Nadja S. , Barbier Estelle , Khomtchouk Bohdan B. , Rienas Christopher A. , Lowe Kenneth , Van Booven Derek J. , Domi Esi , Esanov Rustam , Vilca Samara , Tapocik Jenica D. , Rodriguez Keli , Maryanski Danielle , Keogh Michael Christopher , Meinhardt Marcus W. , Sommer Wolfgang H. , Heilig Markus , Zeier Zane , Wahlestedt Claes
Published: August 2019

Epigenetic enzymes oversee long‐term changes in gene expression by integrating genetic and environmental cues. While there are hundreds of enzymes that control histone and DNA modifications, their potential roles in substance abuse and alcohol dependence remain underexplored. A few recent studies have suggested that epigenetic processes could underlie transcriptomic and behavioral hallmarks of alcohol addiction. In the present study, we sought to identify epigenetic enzymes in the brain that are dysregulated during protracted abstinence as a consequence of chronic and intermittent alcohol exposure. Through quantitative mRNA expression analysis of over 100 epigenetic enzymes, we identified 11 that are significantly altered in alcohol‐dependent rats compared with controls. Follow‐up studies of one of these enzymes, the histone demethylase KDM6B, showed that this enzyme exhibits region‐specific dysregulation in the prefrontal cortex and nucleus accumbens of alcohol‐dependent rats. KDM6B was also upregulated in the human alcoholic brain. Upregulation of KDM6B protein in alcohol‐dependent rats was accompanied by a decrease of trimethylation levels at histone H3, lysine 27 (H3K27me3), consistent with the known demethylase specificity of KDM6B. Subsequent epigenetic (chromatin immunoprecipitation [ChIP]–sequencing) analysis showed that alcohol‐induced changes in H3K27me3 were significantly enriched at genes in the IL‐6 signaling pathway, consistent with the well‐characterized role of KDM6B in modulation of inflammatory responses. Knockdown of KDM6B in cultured microglial cells diminished IL‐6 induction in response to an inflammatory stimulus. Our findings implicate a novel KDM6B‐mediated epigenetic signaling pathway integrated with inflammatory signaling pathways that are known to underlie the development of alcohol addiction.
The immediate efficacy of inhaled nitric oxide treatment in preterm infants with acute respiratory failure during neonatal transport
Authors: Garrido Felipe , Gonzalez‐Caballero Juan Luis , Lomax Rachel , Dady Ian
Published: August 2019

Aim

The aim of our review was to describe the clinical response to inhaled nitric oxide (iNO) in a series of preterm babies in respiratory failure during uplift transfers to a neonatal intensive care unit.

Methods

We performed a retrospective review of critical newborns with gestational age <34+0 weeks transferred from January 2013 to December 2018. Data were extracted from our Clinical Information System for transport. The primary measure of this review was to assess whether a significant improvement in the oxygenation saturation index (OSI) occurred following the use of iNO.

Results

Thirty preterm babies <34+0 weeks were included in our review. OSI, as a measure of oxygenation, did not statistically improve as an immediate response to iNO from referral to receiving hospital (17.1 vs 16.4; P = .7). We found that pH (7.15 vs 7.29; P = .004) and pCO2 (8.1 vs 6.3; P = .05) significantly improved probably based on ventilation management.

Conclusion

Following the recommendations of the American Academy of Paediatrics and other organizations, iNO should not routinely be used during the neonatal transfer of preterm babies <34+0 in respiratory failure. We need to conduct further studies to establish which selected preterm patients would benefit from being treated with iNO.
Barrier damaging effects of n‐propanol in occlusion‐modified tandem repeated irritation test: Modulation by exposure factors and atopic skin disease
Authors: Angelova‐Fischer Irena , Soltanipoor Maryam , Stilla Tasja , Fischer Tobias W. , Kezic Sanja , Jakasa Ivone
Published: August 2019

Background

Recent studies provide evidence for significant and previously underestimated barrier damaging effects of repeated exposure to 60% n‐propanol in healthy skin in vivo.

Objectives

To investigate further the cumulative effects of a range of n‐propanol concentrations relevant at the workplace in healthy and atopic dermatitis (AD) individuals, and study the modulation of the outcomes by co‐exposure and host‐related factors.

Methods

Healthy adult and AD volunteers were exposed to n‐propanol concentrations from 30% to 75% in occlusion‐modified tandem repeated irritation test with measurements of erythema, transepidermal water loss, capacitance, and the natural moisturizing factor (NMF) levels at baseline and after 96 hours.

Results

n‐Propanol exerted significant barrier damaging effects even at the lowest concentration in both groups. Exposure to all n‐propanol concentrations significantly reduced the NMF levels. Preceding low‐grade trauma by occlusion/water exposure reduced the skin irritation threshold in both groups. The differences in the severity of the barrier function impairment after exposure to the same concentrations under the same conditions between the AD and control groups were significant.

Conclusions

The negative effects of cumulative exposure to n‐propanol in healthy and atopic skin shown in the study suggest the need for critical re‐evaluation of its irritant properties in vivo.
Juvenile melanocytic acral nevus: A comparative study between MANIAC and non‐MANIAC nevus and its clinicopathological characteristics
Authors: García‐Rabasco Ana , Roselló‐Añón Alejandro , De‐Unamuno‐Bustos Blanca , Ferrer‐Guillén Blanca , Alegre De Miquel Víctor
Published: August 2019

Background

Melanocytic acral nevi have a series of distinguishing features, including their location, patient age at onset, clinical progression, and histological findings. In particular, histopathological analysis often reveals a melanocytic acral nevus with intraepidermal ascent of cells (MANIAC nevus), which in some cases can be mistaken for atypia or malignancy.

Aim

This study describes the clinicopathological characteristics of acral nevi in patients under 18 years old and contrasts the clinical and histological features between MANIAC vs non‐MANIAC nevi.

Methods

This was a retrospective observational study, performed in our department in the decade between January 2007 and January 2017. We included patients younger than 18 years of age who were subjected to the removal of melanocytic acral nevi.

Results

A total of 70 patients were studied. 54.2% (38/70) were females and 45.8% (32/70) were males. With regard to the type of nevus, 34 were compound, 27 were junctional, and 9 were predominantly intradermal lesions. We identified a total of 41 MANIAC nevi and 29 non‐MANIAC nevi. Statistically significant differences between these two groups were identified in nevus size (larger in MANIAC) and the frequency of compound nevi (higher in the MANIAC group), but not in the remainder of the histological parameters studied.
What can observational data reveal about metacommunity processes?
Authors: Ovaskainen Otso , Rybicki Joel , Abrego Nerea
Published: August 2019

A key challenge for community ecology is to understand to what extent observational data can be used to infer the underlying community assembly processes. As different processes can lead to similar or even identical patterns, statistical analyses of non‐manipulative observational data never yield undisputable causal inference on the underlying processes. Still, most empirical studies in community ecology are based on observational data, and hence understanding under which circumstances such data can shed light on assembly processes is a central concern for community ecologists. We simulated a spatial agent‐based model that generates variation in metacommunity dynamics across multiple axes, including the four classic metacommunity paradigms as special cases. We further simulated a virtual ecologist who analysed snapshot data sampled from the simulations using eighteen output metrics derived from beta‐diversity and habitat variation indices, variation partitioning and joint species distribution modelling. Our results indicated two main axes of variation in the output metrics. The first axis of variation described whether the landscape has patchy or continuous variation, and thus was essentially independent of the properties of the species community. The second axis of variation related to the level of predictability of the metacommunity. The most predictable communities were niche‐based metacommunities inhabiting static landscapes with marked environmental heterogeneity, such as metacommunities following the species sorting paradigm or the mass effects paradigm. The most unpredictable communities were neutral‐based metacommunities inhabiting dynamics landscapes with little spatial heterogeneity, such as metacommunities following the neutral or patch sorting paradigms. The output metrics from joint species distribution modelling yielded generally the highest resolution to disentangle among the simulated scenarios. Yet, the different types of statistical approaches utilized in this study carried complementary information, and thus our results suggest that the most comprehensive evaluation of metacommunity structure can be obtained by combining them.
Aridity, soil and biome stability influence plant ecoregions in the Atlantic Forest, a biodiversity hotspot in South America
Authors: Cantidio Luiza S. , Souza Alexandre F.
Published: August 2019

Our aims were to quantify and map the plant ecoregions of the Atlantic Forest, a biodiversity hotspot that covers ca 150 million ha in eastern South America. We used a data set on the distribution of 4378 shrub and tree species across 711 localities. Plant ecoregions were identified using analyses of species turnover for both species occurrences and relative abundances. We interpolated NMDS axes of compositional variation over the entire the Atlantic Forest extent, and then classified the compositional dissimilarity according to the number of biogeographical ecoregions previously identified through K‐means analyses. We assessed the ability of environmental, historical vegetation stability and the current human footprint to explain the occurrence of the identified ecoregions through multinomial logistic regression models. We identified 21 spatially cohesive occurrence and 14 abundance ecoregions. Aridity, soil and historical biome stability were retained in the best model explaining both occurrence and abundance ecoregions. Broad compositional zones were identified through UPGMA cluster analysis of ecoregions, and formed north and south compositional blocks. Our work confirms the existence of a broad north–south divide within the Atlantic Forest, previously suggested based on climatic and amphibious data. Differences between the occurrence and abundance maps suggest the location of transition zones to neighbouring domains and endemism centres. Due to the aggregate nature of our analyses, site‐level disturbance degree was not considered, implying that human impacts could be broader then we could detect. There was limited overlap between our results and previous Atlantic Forest regionalization efforts, indicating that multi‐taxa, physiognomic and environmental regionalization schemes based on expert opinion or vegetation maps are poor proxies for compositional ecoregions.
Thyroid hormone modulation during zebrafish development recapitulates evolved diversity in danionin jaw protrusion mechanics
Authors: Galindo Demi , Sweet Elly , DeLeon Zoey , Wagner Mitchel , DeLeon Adrian , Carter Casey , McMenamin Sarah K. , Cooper W. James
Published: August 2019

Protrusile jaws are a highly useful innovation that has been linked to extensive diversification in fish feeding ecology. Jaw protrusion can enhance the performance of multiple functions, such as suction production and capturing elusive prey. Identifying the developmental factors that alter protrusion ability will improve our understanding of fish diversification. In the zebrafish protrusion arises postmetamorphosis. Fish metamorphosis typically includes significant changes in trophic morphology, accompanies a shift in feeding niche and coincides with increased thyroid hormone production. We tested whether thyroid hormone affects the development of zebrafish feeding mechanics. We found that it affected all developmental stages examined, but that effects were most pronounced after metamorphosis. Thyroid hormone levels affected the development of jaw morphology, feeding mechanics, shape variation, and cranial ossification. Adult zebrafish utilize protrusile jaws, but an absence of thyroid hormone impaired development of the premaxillary bone, which is critical to jaw protrusion. Premaxillae from early juvenile zebrafish and hypothyroid adult zebrafish resemble those from adults in the genera Danionella, Devario, and Microdevario that show little to no jaw protrusion. Our findings suggest that evolutionary changes in how the developing skulls of danionin minnows respond to thyroid hormone may have promoted diversification into different feeding niches.
The behavioural and social sciences as hidden curriculum in UK dental education: A qualitative study
Authors: Neville Patricia , Zahra Jez , Pilch Katie , Jayawardena Dasna , Waylen Andrea
Published: August 2019

Introduction

The behavioural and social sciences (BeSS) are an integral part of dental curricula, helping students become holistic, patient‐centred practitioners. Nevertheless, UK studies document that dental undergraduates struggle to see the relevance of BeSS to their training. Using the concept of hidden curriculum, this study explored dental studentsâ€™ perceptions of and attitudes towards BeSS in one dental school in the UK.

Material and methods

Six focus groups were conducted with 37 dental students from years 1 to 5. Thematic analysis was conducted revealing five themes: student attitudes towards BeSS, teaching culture, learning culture, curricular issues and student culture.

Results

Many students recognised how BeSS contributed to their communication and patient management skills. Nevertheless, the study revealed a dental student cohort who have a strained relationship with BeSS. This negative attitude became more apparent from year 3 onwards, when the clinical phase of studies begins. It was perpetuated and legitimated by the existence of a strong student culture that openly critiqued BeSS among and between student year groups.

Discussion and conclusion(s)

In UK dental education there is a hidden curriculum related to BeSS. By underestimating the utility of BeSS, students are failing to recognise the biopsychosocial dimensions relevant to oral health and dental practice. All UK dental schools should review their relationship with BeSS and assess whether they are perpetuating a hidden curriculum about BeSS within their curricula.
Self‐reported confidence and anxiety over endodontic procedures in undergraduate students—Quantitative and qualitative study
Authors: Luz Luciana Batista , Grock Camila Hélen , Oliveira Vanessa Farias , Bizarro Lisiane , Ardenghi Thiago Machado , Ferreira Maria Beatriz Cardoso , Montagner Francisco
Published: August 2019

Purpose

The current literature shows a growing interest to assess the feelings and perceptions of students associated with the performance of elective endodontic procedures. This study aimed to evaluate the students' anxiety and self‐perceptions related to performing such treatments.

Methods

Forty‐five students participated in the research (G1 = 22 beginners students; G2 = 23 senior students). Demographic data, STAI‐State and Numerical Rating Scale (NRS) for pre‐operative anxiety were completed before the appointment with patient. The STAI‐Trait; NRS for post‐operative anxiety; previous experiences in endodontics; and level of confidence in each stage of endodontic treatments were collected after appointment. Focal groups for qualitative data collection were performed on separate occasion.

Results

Both groups showed higher scores in STAI‐State than for STAI‐Trait scale. G1 showed higher levels of anxiety in the pre‐operative, compared with post‐operative moment in the NRS scale. G2 reported feeling more confidence to insert intracanal medication and to restore teeth between appointments than G1. In both focus groups, participants reported insecurity in performing endodontic procedures due to difficulty in visualisation and to anatomic complexities. G1 reported that all the confidence they had was based in pre‐clinical experience, and G2 mentioned concern about the end of graduation.

Conclusion

The participants' anxiety diminishes as they gain more experience in performing endodontic procedures. However, as they approach the end of the course anxiety levels increase. Greater availability of elective courses in endodontics could be a valuable alternative to provide students with more exposure to and experience with these procedures.
Determinants of knowledge and practice of forensic dentistry amongst dental practitioners
Authors: Nazir Muhammad Ashraf , Al‐Ansari Asim , Al‐Khalifa Khalifa , Gaffar Balgis Osman
Published: August 2019

Objective

To evaluate the determinants of knowledge and practice of forensic dentistry (FD) amongst dental practitioners.

Methods

This cross‐sectional study was conducted on dental practitioners working in private and public sectors in the Eastern province of Saudi Arabia. A pilot tested self‐administered questionnaire was distributed amongst an estimated sample of 323 dentists. Bivariate and multivariable logistic regression analyses were performed.

Results

In the study, 72.4% of the estimated sample returned completed questionnaires. There were 142 male (60.7%) and 92 female dentists (39.3%) in the study. There were 59 (25.2%) dentists who had the knowledge of FD and 27 (11.5%) handled the cases related to FD. Multivariable logistic regression showed that receiving FD training in undergraduate program (Adjusted odd ratio [AOR] = 10.31, 95% CI = 4.67‐22.76), and updating the information of FD (AOR = 6.68, 95% CI = 2.81‐15.86) were significantly associated with increased odds of having the knowledge of FD. Similarly, updating the information of FD (AOR = 7.56, 95% CI = 2.54‐22.51) and having ≥5 years of clinical experience (AOR = 4.64, 95% CI = 1.00‐21.40) were significant determinants of handling the cases of FD. The adjusted odds ratio for the maintenance of dental records was 4.16 times higher for specialists and consultants than general dentists.

Conclusion

The study found that the dentists who received FD training had greater chances of having FD knowledge. Updating information about FD was associated with improved knowledge and practice of FD. Dental curricula should provide knowledge and skills of FD to students in undergraduate programs and the dentists should learn about FD through different educational sources.
Transcriptional profiling aligned with in situ expression image analysis reveals mosaically expressed molecular markers for GABA neuron sub‐groups in the ventral tegmental area
Authors: Paul Eleanor J. , Tossell Kyoko , Ungless Mark A.
Published: August 2019

γ‐Aminobutyric acid (GABA) neurons in the ventral tegmental area (VTA) provide local inhibitory control of dopamine neuron activity and send long‐range projections to several target regions including the nucleus accumbens. They play diverse roles in reward and aversion, suggesting that they be comprised of several functionally distinct sub‐groups, but our understanding of this diversity has been limited by a lack of molecular markers that might provide genetic entry points for cell type‐specific investigations. To address this, we conducted transcriptional profiling of GABA neurons and dopamine neurons using immunoprecipitation of tagged polyribosomes (RiboTag) and RNAseq. First, we directly compared these two transcriptomes in order to obtain a list of genes enriched in GABA neurons compared with dopamine neurons. Next, we created a novel bioinformatic approach, that used the PANTHER (Protein ANalysis THrough Evolutionary Relationships) gene ontology database and VTA gene expression data from the Allen Mouse Brain Atlas, from which we obtained 6 candidate genes: Cbln4, Rxfp3, Rora, Gpr101, Trh and Nrp2. As a final step, we verified the selective expression of these candidate genes in sub‐groups of GABA neurons in the VTA (and neighbouring substantia nigra pars compacta) using immunolabelling. Taken together, our study provides a valuable toolbox for the future investigation of GABA neuron sub‐groups in the VTA.
Supporting the evaluation of public and patient engagement in health system organizations: Results from an implementation research study
Authors: Abelson Julia , Tripp Laura , Kandasamy Sujane , Burrows Kristen ,   on behalf of the PPEET Implementation Study Team
Published: August 2019

Background

As citizens, patients and family members are participating in numerous and expanding roles in health system organizations, attention has turned to evaluating these efforts. The context‐specific nature of engagement requires evaluation tools to be carefully designed for optimal use. We sought to address this need by assessing the appropriateness and feasibility of a generic tool across a range of health system organizations, engagement activities and patient groups.

Methods

We used a mixed‐methods implementation research design to study the implementation of an engagement evaluation tool in seven health system organizations in Ontario, Canada focusing on two key implementation outcome variables: appropriateness and feasibility. Data were collected through respondent feedback questions (binary and open‐ended) at the end of the tool's three questionnaires as well as interviews and debriefing discussions with engagement professionals and patient partners from collaborating organizations.

Results

The three questionnaires comprising the evaluation tool were collectively administered 29 times to 405 respondents yielding a 52% response rate (90% and 53% of respondents respectively assessed the survey's appropriateness and feasibility [quantitatively or qualitatively]). The questionnaires' basic properties were rated highly by all respondents. Concrete suggestions were provided for improving the appropriateness and feasibility of the questionnaires (or components within) for different engagement activity and organization types, and for enhancing the timing of implementation.

Discussion and Conclusions

Our study findings offer guidance for health system organizations and evaluators to support the optimal use of engagement evaluation tools across a variety of health system settings, engagement activities and respondent groups.
Distributional dynamics of a specialized subterranean community oppose the classical understanding of the preferred subterranean habitats
Authors: Kozel Peter , Pipan Tanja , Mammola Stefano , Culver David C. , Novak Tone
Published: August 2019

Troglobionts are organisms that are specialized for living in a subterranean environment. These organisms reside prevalently in the deepest zones of caves and in shallow subterranean habitats, and complete their entire life cycles therein. Because troglobionts in most caves depend on organic matter resources from the surface, we hypothesized that they would also select the sections of caves nearest the surface, as long as environmental conditions were favorable. Over 1 year, we analyzed, in monthly intervals, the annual distributional dynamics of a subterranean community consisting of 17 troglobiont species, in relation to multiple environmental factors. Cumulative standardized annual species richness and diversity clearly indicated the existence of two ecotones within the cave: between soil and shallow subterranean habitats, inhabited by soil and shallow troglobionts; and between the transition and inner cave zones, where the spatial niches of shallow and deep troglobionts overlap. The mean standardized annual species richness and diversity showed inverse relationships, but both contributed to a better insight into the dynamics of subterranean fauna. Regression analyses revealed that temperatures in the range 7–10°C, high moisture content of substrate, large cross section of the cave, and high pH of substrate were the most important ecological drivers governing the spatiotemporal dynamics of troglobionts. Overall, this study shows general trends in the annual distributional dynamics of troglobionts in shallow caves and reveals that the distribution patterns of troglobionts within subterranean habitats may be more complex than commonly assumed.
Cyclophilin D participates in the inhibitory effect of high‐fat diet on the expression of steroidogenic acute regulatory protein
Authors: Su Xiaohui , Lin Dong , Luo Dandan , Sun Mingqi , Wang Xiaolei , Ye Jifeng , Zhang Meijie , Zhang Yikun , Xu Xiaolin , Yu Chunxiao , Guan Qingbo
Published: August 2019

Objective

The high‐fat diet (HFD)–induced obesity is responsible for the testosterone deficiency (TD). However, the mechanism remains unknown. Mitochondrial homeostasis is proved to be important for maintaining the function of steroidogenic acute regulatory protein (StAR), the first rate‐limiting enzyme in testosterone synthesis. As the key regulator of mitochondrial membrane permeability, cyclophilin D (CypD) plays a crucial role in maintaining mitochondrial function. In this study, we sought to elucidate the role of CypD in the expression of StAR affected by HFD.

Methods

To analyse the influence of CypD on StAR in vivo and in vitro, mouse models of HFD, CypD overexpression and CypD knockout (Ppif−/−) as well as Leydig cells treated with palmitic acid (PA) and CypD overexpression plasmids were examined with an array of metabolic, mitochondrial function and molecular assays.

Results

Compared with the normal diet mice, consistent with reduced testosterone in testes, the expressions of StAR in both mRNA and protein levels in HFD mice were down‐regulated, while expressions of CypD were up‐regulated. High‐fat intake impaired mitochondrial function with the decrease in StAR in Leydig cells. Overexpression of CypD inhibited StAR expressions in vivo and in vitro. Compared with C57BL/6 mice with HFD, expressions of StAR were improved in Ppif−/− mice with HFD.

Conclusions

Mitochondrial CypD involved in the inhibitory effect of HFD on StAR expression in testes.
Annual Research Review: A meta‐analytic review of worldwide suicide rates in adolescents
Authors: Glenn Catherine R. , Kleiman Evan M. , Kellerman John , Pollak Olivia , Cha Christine B. , Esposito Erika C. , Porter Andrew C. , Wyman Peter A. , Boatman Anne E.
Published: August 2019

Suicide is a leading cause of death among youth worldwide. The purpose of the current review was to examine recent cross‐national trends in suicide mortality rates among 10‐ to 19‐year‐olds. This study extracted suicide mortality data from the World Health Organization's (WHO) Mortality Database for the most recent year (since 2010) from any country with available high‐quality data (as defined by the WHO's guidelines). Data on access to lethal means (firearms, railways) and measures of economic quality (World Bank Income Group) and inequality (Gini coefficients) were obtained from publicly available data sources. Cross‐national suicide mortality rates in youth were heterogeneous. The pooled estimate across all ages, sexes, and countries was 3.77/100,000 people. The highest suicide rates were found in Estonia, New Zealand, and Uzbekistan. Suicide rates were higher among older compared with younger adolescents and higher among males than females. The most common suicide methods were hanging/suffocation and jumping/lying in front of a moving object or jumping from a height. Firearm and railway access were related to suicide deaths by firearms and jumping/lying, respectively. Economic quality and inequality were not related to overall suicide mortality rates. However, economic inequality was correlated with a higher ratio of male:female suicides. This study provides a recent update of cross‐national suicide trends in adolescents. Findings replicate prior patterns related to age, sex, geographic region, and common suicide methods. New to this review are findings relating suicide method accessibility to suicide mortality rates and the significant association between income inequality and the ratio of male:female suicide. Future research directions include expanding the worldwide coverage to more low‐ and middle‐income countries, examining demographic groupings beyond binary sex and to race/ethnicity within countries, and clarifying factors that account for cross‐national differences in suicide trends.
HEADS I WIN, TAILS YOU LOSE: INSTITUTIONAL MONITORING OF EXECUTIVE PAY RIGIDITY
Authors: Choi Paul Moon Sub , Chung Chune Young , Hwang Ji Hoon , Liu Chang
Published: August 2019

Agency theory argues that pay for performance alleviates the conflict of interest between managers and shareholders. Furthermore, the literature finds that institutional monitoring tends to promote the performance–pay linkage, thus aligning the two parties’ incentives. We find that executive compensation rigidity is negatively and significantly associated with firm value. Moreover, ownership by long‐term institutional investors reduces the pay rigidity of top managers in underperforming firms, thus decreasing the value‐destroying effect of the rigidity. Overall, these results reaffirm the role of institutional monitoring in mitigating managerial rent extraction.