bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibitors of DAG metabolism suppress CCR2 signalling in human monocytes
Authors: Day Priscilla , Burrows Lisa , Richards David , Fountain Samuel J.
Published: April 2019

Background and Purpose

CCL2 is an inflammatory chemokine that stimulates the recruitment of monocytes into tissue via activation of the GPCR CCR2.

Experimental Approach

Freshly isolated human monocytes and THP‐1 cells were used. Fura‐2 loaded cells were used to measure intracellular Ca2+ responses. Transwell migration to measure chemotaxis. siRNA‐mediated gene knock‐down was used to support pharmacological approaches.

Key Results

CCL2 evoked intracellular Ca2+ signals and stimulated migration in THP‐1 monocytic cells and human CD14+ monocytes in a CCR2‐dependent fashion. Attenuation of DAG catabolism in monocytes by inhibiting DAG kinase (R59949) or DAG lipase (RHC80267) activity suppressed CCL2‐evoked Ca2+ signalling and transwell migration in monocytes. These effects were not due to a reduction in the number of cell surface CCR2. The effect of inhibiting DAG kinase or DAG lipase could be mimicked by addition of the DAG analogue 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG) but was not rescued by application of exogenous phosphatidylinositol 4,5‐bisphosphate. Suppressive effects of R59949, RHC80267, and OAG were partially or fully reversed by Gö6983 (pan PKC isoenzyme inhibitor) but not by Gö6976 (PKCα and PKCβ inhibitor). RNAi‐mediated knock‐down of DAG kinase α isoenzyme modulated CCL2‐evoked Ca2+ responses in THP‐1 cells.

Conclusions and Implications

Taken together, these data suggest that DAG production resulting from CCR2 activation is metabolised by both DAG kinase and DAG lipase pathways in monocytes and that pharmacological inhibition of DAG catabolism or application suppresses signalling on the CCL2–CCR2 axis via a mechanism dependent upon a PKC isoenzyme that is sensitive to Gö6983 but not Gö6976.
Phylogeny and diversification of the true water bugs (Insecta: Hemiptera: Heteroptera: Nepomorpha)
Authors: Ye Zhen , Damgaard Jakob , Yang Huanhuan , Hebsgaard Martin B. , Weir Tom , Bu Wenjun
Published: April 2019

Climate fluctuations and tectonic reconfigurations associated with environmental changes play large roles in determining patterns of adaptation and diversification, but studies documenting how such drivers have shaped the evolutionary history and diversification dynamics of limnic organisms during the Mesozoic are scarce. Members of the heteropteran infraorder Nepomorpha, or aquatic bugs, are ideal for testing the effects of these determinants on their diversification pulses because most species are confined to aquatic environments during their entire life. The group has a relatively mature taxonomy and is well represented in the fossil record. We investigated the evolution of Nepomorpha based on phylogenetic analyses of morphological and molecular characters sampled from 115 taxa representing all 13 families and approximately 40% of recognized genera. Our results were largely congruent with the phylogenetic relationships inferred from morphology. A divergence dating analysis indicated that Nepomorpha began to diversify in the late Permian (approximately 263 Ma), and diversification analyses suggested that palaeoecological opportunities probably promoted lineage diversification in this group.
Synchrony patterns reveal different degrees of trophic guild vulnerability after disturbances in a coral reef fish community
Authors: Viviani Jérémie , Moritz Charlotte , Parravicini Valeriano , Lecchini David , Siu Gilles , Galzin René , Viriot Laurent
Published: April 2019

Aim

Chronic anthropogenic stressors are increasing in intensity, making ecosystems more vulnerable to acute disturbances. Recovery processes are not always well understood due to the complexity of ecosystems and the lack of appropriate indicators. Temporal synchrony is a valuable metric for assessing whether fluctuations in abundance of different species are homogeneous or heterogeneous over time. Theoretically, a great diversity of responses by species facing disturbances is associated with a stable ecosystem, with species turnover guaranteeing the persistence of key ecological processes. We analysed the fluctuations of synchrony of a fish community to assess its resilience in an ecosystem exposed to various disturbances.

Location

Moorea (French Polynesia).

Methods

Using one of the longest time series available for coral reefs (ca. 35 years), we examined the variations in substrate cover, and the abundance, synchrony and composition of different fish trophic guilds. Multivariate analyses involving synchrony were used to determine the stability of trophic guilds.

Results

Changes in fish community composition indicated incomplete taxonomic resilience. However, community synchrony was lower during periods of low coral cover, indicating greater response diversity, while total fish abundance remained fairly stable. Synchrony drop was due to relationships with coral cover that differed by trophic guild, or the differences in species responses within guilds. Some guilds such as sessile invertebrate feeders exhibited a strong homogeneity of response over time, indicating a greater vulnerability. We also highlighted that various types of disturbances had different effects on the synchrony of particular guilds.

Main conclusions

The fish community appeared functionally resilient, with stability of total abundance and most trophic guilds. This could be a factor explaining the rapid recovery of Moorea's coral reefs from disturbances. However, the homogeneous responses of some fish groups to disturbances may compromise the reef recovery potential on the long term if disturbances become more frequent.
INFLATION DYNAMICS AND THE OUTPUT‐INFLATION TRADE‐OFF: INTERNATIONAL PANEL DATA EVIDENCE
Authors: Bakas Dimitrios , Chortareas Georgios
Published: April 2019

We explore the impact of inflation and its variability on the output‐inflation trade‐off using a single‐step approach in a panel data context. Previous empirical approaches focus on either cross‐country or country‐by‐country time‐series analyses. We employ a dynamic heterogeneous panel specification using an all‐encompassing estimation framework accounting for parameter heterogeneity, cross‐sectional dependence, dynamics, and nonstationarity. Our sample covers 60 countries from 1970 to 2010. While inflation variability reduces the trade‐off for specific periods and country groups, an unambiguous and more pronounced negative relation emerges between the inflation rate and the trade‐off. The findings are consistent with the New Keynesian view. (JEL E31, E12, C23)
Global distribution patterns of mycoheterotrophy
Authors: Gomes Sofia I. F. , van Bodegom Peter M. , Merckx Vincent S. F. T. , Soudzilovskaia Nadejda A.
Published: April 2019

Aim

Mycoheterotrophy is a mode of life where plants cheat the mycorrhizal symbiosis, receiving carbon via their fungal partners. Despite being widespread, mycoheterotrophic plants are locally rare, hampering the understanding of their global environmental drivers. Here, we explore global environmental preferences of mycoheterotrophy, and investigate environmental drivers of differential habitat preferences of mycoheterotrophic plants associated with arbuscular (AM) and ectomycorrhizal (EM) fungi.

Location

Global.

Time period

Current.

Major taxa studied

Mycoheterotrophic flowering plants.

Methods

We compiled the largest global dataset of epiparasitic mycoheterotrophic plant species occurrences and examined which environmental factors, including soil type, climate, vegetation type and distribution patterns of mycorrhizal autotrophic plants, relate to occurrence patterns of mycoheterotrophic plant species associated with AM and EM fungi.

Results

Mycoheterotrophic plant species avoid cold and highly seasonal climates and show a strong preference for forests. AM‐associated mycoheterotrophs are predominantly found in broadleaved tropical evergreen forests whereas EM‐associated mycoheterotrophs occur in temperate regions, mostly in broadleaved deciduous and evergreen needleleaved forests. The abundance of AM and EM autotrophic plants was a weaker predictor for mycoheterotrophs occurrences than forest type. Temperature and precipitation variables – but not edaphic factors – were the best predictors explaining the distribution patterns of mycoheterotrophs after accounting for the effects of forest type. For individual lineages, major differences in environmental preferences (often related to edaphic factors) occurred that were significantly associated with plant evolutionary relationships, indicating that these cheater plants have limited adaptive capabilities.

Main conclusions

The strong global geographical segregation of AM and EM mycoheterotrophs does not reflect the abundance of their potential autotrophic hosts, but seems to be driven by differential climate and habitat preferences. Our results highlight the non‐trivial nature of mycorrhizal interactions, and indicate that identity of the partners is not enough to understand the underlying mechanisms promoting plant–fungal interactions in mycoheterotrophic plants.
Supporting self‐management after traumatic brain injury: Codesign and evaluation of a new intervention across a trauma pathway
Authors: Mäkelä Petra , Jones Fiona , de Sousa de Abreu Maria Inês , Hollinshead Lucinda , Ling John
Published: April 2019

Background

Supported self‐management (SSM) is a recognized approach for people with long‐term conditions but, despite the prevalence of unmet needs, little is known about its role for people with traumatic brain injury (TBI).

Objectives

To codesign an SSM intervention with people with TBI and evaluate feasibility of implementation through multidisciplinary staff across a trauma pathway.

Setting and participants

People who had previously been admitted to a Major Trauma Centre following TBI and family members participated in a series of codesign activities. Staff attended SSM workshops and used the intervention with patients in acute and rehabilitation settings.

Methods

We used Normalization Process Theory constructs to guide and interpret implementation. Knowledge, beliefs and confidence of staff in SSM were assessed through pre‐ and post‐training questionnaires, and staff, patients' and families' experiences were explored through semi‐structured interviews. Qualitative data were analysed thematically, and clinical measures were mapped against a matched sample.

Results

Codesigned resources were created and used within an SSM approach for which 110 staff participated in training. Evaluation demonstrated significant differences in staff SSM confidence and skills, following training. Qualitative evaluation revealed adoption by staff, and patients' and families' experiences of using the resources. Challenges included reaching staff across complex pathways to achieve collective implementation.

Conclusion

This is the first project to demonstrate feasibility of SSM for people after TBI starting in an acute trauma setting. Through an open approach to codesign with a marginalized group, the SSM resources were valued by them and held meaning and relevance for staff.
Social health protection in Cambodia: Challenges of policy design and implementation
Authors: Kwon Soonman , Keo Lundy
Published: April 2019

The Government of Cambodia is implementing ambitious reform initiatives to improve the country's social health protection system. In January 2018, it was announced that the Health Equity Fund (HEF), which is fully subsidized by a joint government‐donor initiative for the reimbursement of user fees for the poor at public health facilities, is to be expanded to some segments of informal workers belonging to associations, as well as to commune and village chiefs. Since 2017, the National Social Security Fund (NSSF) has provided social health insurance for formal economy workers in enterprises with eight employees or more. In January 2018, it was expanded to civil servants and all employees regardless of the size of the enterprise. However, this article highlights that the new ambitious reforms are not accompanied by careful planning as regards funding, service delivery, human resources and institutional design. This article therefore aims to examine key policy issues and challenges for Cambodia's ambitious reform of its social health protection system in terms of resource generation, population coverage, strategic purchasing and governance.
Sustaining Power of Nurses in a Damaged Hospital During the Great East Japan Earthquake
Authors: Nakayama Yoko , Kato Ikuko , Ohkawa Takako
Published: April 2019

Purpose

This study aimed to describe the experiences of nurses who were employed in a psychiatric hospital in Fukushima prefecture during the Great East Japan Earthquake and to explore what sustained the nurses while they worked in the damaged hospital.

Design and Methods

The research design was a qualitative descriptive study. The setting for the study was one of the Fukushima psychiatric hospitals where functions were disrupted by the earthquake and tsunami. Data were collected through a dialogic interview and Katarai (a form of group interview). Nine psychiatric nurses from the hospital participated. The interview and Katarai were transcribed and the narratives were analyzed using a phenomenological approach.

Findings

Themes identified from the transcripts were: (a) the nurses’ internalized perception of their duties, (b) responsibility toward their patients, (c) conflicts among nurses and dilemmas nurses faced during this period, and (d) what sustained the nurses to continue working.

Conclusions

Through the earthquake experience, the nurses in this study reconsidered their own ways of living and ways of nursing that they had not thought about before the disaster. The findings also revealed that the state of hospital management and nursing care under normal conditions are reflected during the crisis situation in a disaster.

Clinical Relevance

Clearly, whether it is natural disaster or conflict caused by man, healthcare infrastructures are challenged when unexpected disruptions occur. The findings of this study are applicable not only because they provide guidance about infrastructure development for disaster preparedness, but also because they provide practical methods to support nurses who are placed in strongly stressful situations and have to protect patients.
A Social Gradient in the Effects of the Skills for Life Program on Self‐Efficacy and Mental Wellbeing of Adolescent Students
Authors: Pannebakker Fieke D. , van Genugten Lenneke , Diekstra René F. W. , Gravesteijn Carolien , Fekkes Minne , Kuiper Rebecca , Kocken Paul L.
Published: April 2019

BACKGROUND

The goal of the current study was to evaluate the effects of the Social Emotional Learning program Skills 4 Life on mental health and its risk factors self‐esteem, self‐efficacy, and social interaction skills in students of secondary schools.

METHODS

A cluster randomized controlled study was conducted, including 38 schools (66 classes; grades 7 to 9) for secondary education, with a 1 year and 20 months follow‐up (teachers and students reports).

RESULTS

The intervention was effective in improving self‐efficacy, depressive symptoms, and teacher‐reported psychological problem behavior, all after 20 months. Stratified analyses showed effects in mainly lower educational level students.

CONCLUSION

The Skills 4 Life curriculum is effective in improving the mental health and self‐efficacy among adolescents, especially for adolescents from lower educational level, a group that is most prone to ill mental health.
The Interplay between the One and the Others: Multiple Cultural Identifications and Social Networks
Authors: Repke Lydia , Benet‐Martínez Verónica
Published: April 2019

This article proposes a social network approach to the study of multiple cultural identifications. We argue that social network theory and social network methodology are essential for a truly dynamic examination of how multiple cultural identifications develop and how they are negotiated. This article starts by defining some relevant concepts (i.e., cultural identification, Bicultural Identity Integration, social networks), and then goes on to integrate these concepts into a micro–meso‐level framework by discussing the bidirectional links between cultural identifications and social networks (i.e., their content and their structure). We, then, explicate how social and cultural psychology can gain theoretically and methodologically from social network analysis. Finally, we conclude with some recommendations for researchers who seek to include social networks in their approach, and also discuss general and specific policy implications.
Flushing of peripheral intravenous catheters: A pilot, factorial, randomised controlled trial of high versus low frequency and volume in paediatrics
Authors: Kleidon Tricia M , Keogh Samantha , Flynn Julie , Schults Jessica , Mihala Gabor , Rickard Claire M
Published: April 2019

Aim

To test the feasibility of an efficacy trial comparing different flushing frequencies and volumes to reduce peripheral intravenous cannula (PIVC) failure in paediatric inpatients.

Methods

Pilot, 2 × 2 factorial, randomised controlled trial comparing PIVC flushing techniques in intervention pairs: (i) low volume (3 mL) versus high volume (10 mL); and (ii) low frequency (24 hourly) versus high frequency (6 hourly). Patients were excluded if: fluids were restricted, weight < 5 kg, PIVC already in situ for >24 h or continuous infusion. The primary end‐point was feasibility (eligibility, recruitment, retention, protocol adherence, missing data and sample size estimates) of a large trial. Secondary end‐points were PIVC failure (composite and individual), bloodstream infection and mortality.

Results

A total of 919 children were screened from April to November 2015, with 55 enrolled. Screening feasibility criteria were not met, mainly due to continuous infusions and PIVCs in situ >24 h or planned for imminent removal. However, 80% of eligible participants consented, 2% withdrew, protocol adherence was 100%, and there was no missing primary end‐point data. PIVC failure was significantly higher (hazard ratio = 2.90, 95% confidence interval: 1.11–7.54) in the 3 mL compared to the 10 mL group. There was no difference in failure between frequency groups (hazard ratio = 0.91, 95% confidence interval: 0.36–2.33). There was no interaction effect (P = 0.22).

Conclusion

Trial feasibility proved challenging due to eligibility criteria, which could be improved with additional recruiting staff. Firm conclusions cannot be made based on this small sample, but flush volume may impact PIVC failure.
In vitro evaluation of complement deposition and opsonophagocytic killing of Rhodococcus equi mediated by poly‐N‐acetyl glucosamine hyperimmune plasma compared to commercial plasma products
Authors: Folmar Chelsea N. , Cywes‐Bentley Colette , Bordin Angela I. , Rocha Joana N. , Bray Jocelyne M. , Kahn Susanne K. , Schuckert Amanda E. , Pier Gerald B. , Cohen Noah D.
Published: April 2019

Background

The bacterium Rhodococcus equi can cause severe pneumonia in foals. The absence of a licensed vaccine and limited effectiveness of commercial R. equi hyperimmune plasma (RE‐HIP) create a great need for improved prevention of this disease.

Hypothesis

Plasma hyperimmune to the capsular polysaccharide poly‐N‐acetyl glucosamine (PNAG) would be significantly more effective than RE‐HIP at mediating complement deposition and opsonophagocytic killing (OPK) of R. equi.

Animals

Venipuncture was performed on 9 Quarter Horses.

Methods

The ability of the following plasma sources to mediate complement component 1 (C1) deposition onto either PNAG or R. equi was determined by ELISA: (1) PNAG hyperimmune plasma (PNAG‐HIP), (2) RE‐HIP, and (3) standard non‐hyperimmune commercial plasma (SP). For OPK, each plasma type was combined with R. equi, equine complement, and neutrophils isolated from horses (n = 9); after 4 hours, the number of R. equi in each well was determined by quantitative culture. Data were analyzed using linear mixed‐effects regression with significance set at P < .05.

Results

The PNAG‐HIP and RE‐HIP were able to deposit significantly (P < .05) more complement onto their respective targets than the other plasmas. The mean proportional survival of R. equi opsonized with PNAG‐HIP was significantly (P < .05) less (14.7%) than that for SP (51.1%) or RE‐HIP (42.2%).

Conclusions and Clinical Importance

Plasma hyperimmune to PNAG is superior to RE‐HIP for opsonizing and killing R. equi in vitro. Comparison of these 2 plasmas in field trials is warranted because of the reported incomplete effectiveness of RE‐HIP.
In search of leisure time: An endogenous growth model with leisure services
Authors: Candela Guido , Castellani Massimiliano , Dieci Roberto
Published: April 2019

Starting from the Ladrón‐de Guevara et al.’s framework, we develop a model with an additional sector for the production of leisure services. By introducing consumption of leisure services as a time‐consuming activity, our model generalizes the standard time allocation problem whereby total available time can be allocated between work, education, free time and leisure activities. We analytically characterize the balanced growth paths of the model, particularly in terms of time allocation and growth. Our comparative analysis of different service economies assumed at equilibrium includes the case of an industrial economy without a service sector and the potential multiple equilibria of such an economy.
Water is and is not H2O
Authors: Tobia Kevin P. , Newman George E. , Knobe Joshua
Published: April 2019

The Twin Earth thought experiment invites us to consider a liquid that has all of the superficial properties associated with water (clear, potable, etc.) but has entirely different deeper causal properties (composed of “XYZ” rather than of H2O). Debates about natural kind concepts have sought to accommodate an apparent fact about ordinary people's judgments: Intuitively, the Twin Earth liquid is not water. We present results showing that people do not have this intuition. Instead, people tend to judge that there is a sense in which the liquid is not water but also a sense in which itiswater.
Chewing lice from high‐altitude and migrating birds in Yunnan, China, with descriptions of two new species of Guimaraesiella
Authors: Gustafsson D. R. , Lei L. , Luo K. , Chu X. , Zhao X. , Zhang Q. , Zou F.
Published: April 2019

In total, 366 birds representing 55 species in 24 families and eight orders, were examined for chewing lice (Phthiraptera: Amblycera, Ischnocera) in two high‐altitude localities in Yunnan Province, China. In Ailaoshan, almost all of the birds examined were resident passeriforms, of which 36% were parasitized by chewing lice. In Jinshanyakou, most birds were on migration, and included both passerine and non‐passerine birds. Of the passerine birds caught in Jinshanyakou, only one bird (0.7%) was parasitized by chewing lice. The prevalence of Myrsidea and Brueelia‐complex lice on birds caught in Ailaoshan was higher than in previous reports. Of the chewing lice identifiable to species level, three represent new records for China: Actornithophilus hoplopteri (Mjöberg, 1910), Maculinirmus ljosalfar Gustafsson & Bush, 2017 and Quadraceps sinensis Timmermann, 1954. In total, 17 new host records are included, of which we describe two as new species in the Brueelia‐complex: Guimaraesiella (Cicchinella) ailaoshanensis sp. nov. ex Schoeniparus dubius dubius (Hume, 1874) and G. (C.) montisodalis sp. nov. ex Fulvetta manipurensis tonkinensis Delacour & Jabouille, 1930.

This published work has been registered in ZooBank,
http://zoobank.org/urn:lsid:zoobank.org:pub:9FC3D8EE‐2CED‐4DBE‐A1DB‐471B71260D27.
The Lost Years: The American Peace Movement, From Vietnam to Nuclear Freeze
Authors: Maar Henry Richard
Published: April 2019

This article resurrects the lost years of the American peace movement in the wake of the Vietnam War. It follows the efforts of activists to launch a peace conversion campaign as the answer to American militarism, for which the Vietnam War was only a symptom. Through analysis of various archival holdings, this study demonstrates the historical significance of grassroots peace activism over the course of the 1970s—a period largely viewed through the lens of conservative ascendancy. These campaigns successfully pushed back against major weapons systems such as the B‐1 bomber and the MX missile, while further making the question of war and peace central to American politics by the 1980 presidential election.
Lack-of-Fit Tests for Quantile Regression Models
Authors: Dong Chen , Li Guodong , Feng Xingdong
Published: April 2019

The paper novelly transforms lack-of-fit tests for parametric quantile regression models into checking the equality of two conditional distributions of covariates. Accordingly, by applying some successful two-sample test statistics in the literature, two tests are constructed to check the lack of fit for low and high dimensional quantile regression models. The low dimensional test works well when the number of covariates is moderate, whereas the high dimensional test can maintain the power when the number of covariates exceeds the sample size. The null distribution of the high dimensional test has an explicit form, and the p-values or critical values can then be calculated directly. The finite sample performance of the tests proposed is examined by simulation studies, and their usefulness is further illustrated by two real examples.
Jurassic igneous rocks of the central Sanandaj–Sirjan zone (Iran) mark a propagating continental rift, not a magmatic arc
Authors: Azizi Hossein , Stern Robert J.
Published: April 2019

Jurassic igneous bodies of the Sanandaj–Sirjan zone (SaSZ) in SW Iran are generally considered as a magmatic arc but critical evaluation of modern geochronology, geochemistry and radiogenic isotopes challenges this conclusion. There is no evidence for sustained igneous activity along the ~1,200 km long SaSZ, as expected for a convergent plate margin; instead activity was brief at most sites and propagated NW at ~20 mm/a. Jurassic igneous rocks define a bimodal suite of gabbro‐diorite and granite. Chemical and isotopic compositions of mafic rocks indicate subcontinental lithospheric mantle sources that mostly lacked subduction‐related modifications. The arc‐like features of S‐type granites reflect massive involvement of Cadomian crust and younger sediments to generate felsic melts in response to mafic intrusions. We conclude that Jurassic SaSZ igneous activity occurred in a continental rift, not an arc. SaSZ igneous rocks do not indicate that subduction along the SW margin of Eurasia began in Jurassic time.
A review of acupuncture in obstetrics and gynaecology
Authors: Karim Faisal , Dilley James , Cheung Elaine
Published: April 2019

Key content

Acupuncture is an ancient form of medicine involving sensory stimulation via needle insertion.

In the UK, Western medical acupuncture (WMA), an adaptation of traditional Chinese approach, is used in varying circumstances, including in obstetrics and gynaecology.

Outcome studies have demonstrated that acupuncture can be effective in pain management, fertility and obstetrics (during pregnancy, intrapartum and postpartum).

Acupuncture is safe and has a very low risk of adverse incidents if carried out by trained and accredited practitioners.

Learning objectives

To understand that there is a different but complementary option available when treatment success is not achieved with Western medicine and that women may opt for acupuncture over more recognised treatment options.

To be aware that studies have shown that acupuncture can be a beneficial treatment, but most studies are non‐randomised.

Ethical issues

Women should be given information about all suitable treatments, including acupuncture, to make an informed choice.
Evaluation of Turkish Teacher Candidates' Usage of Complex Sentences Containing “ki” Conjunction in Turkish
Authors: Uyanik Osman
Published: April 2019

The purpose of this study is to evaluate the Turkish teacher candidates’ usage of Turkish complex sentences with “ki” conjunction, which are one of the most commonly used sentence patterns in Turkish.The Turkish language has been interacting with different languages for centuries. There are two types of “ki” conjunctions in Turkish. One of them originated from Turkish and the other one was transferred from Persian to Turkish. There is a difference between the "ki" conjunction taken from Persian language and the one which originated from Turkish language. With this research, it is aimed to determine whether students use these two different “ki” conjuctions in their sentences correctly or not. While the “ki” conjunction which was transferred from Persian to Turkish is used for making description sentences, the “ki” conjunction belonging to Turkish is used to make cause-effect sentences.In this study, a number of Turkish teacher candidates were asked to write compositions containing sentences with “ki” conjunction. The study group consisted of 11 female and 9 male Turkish Teacher Candidates. Data were collected through qualitative research methods and analyzed by document analysis and descriptive analysis.According to the research results the “ki” conjunction used in sentences by Turkish teacher candidates do not conform to the sentence structure of Persian, but do conform to the sentence structure of Turkish. As a result, it can be said that Turkish teacher candidates should use sentences with “ki” conjunction by taking this difference into consideration.
Autoequivalences of twisted K3 surfaces
Authors: Reinecke Emanuel
Published: April 2019

Derived equivalences of twisted K3 surfaces induce twisted Hodge isometries between them; that is, isomorphisms of their cohomologies which respect certain natural lattice structures and Hodge structures. We prove a criterion for when a given Hodge isometry arises in this way. In particular, we describe the image of the representation which associates to any autoequivalence of a twisted K3 surface its realization in cohomology: this image is a subgroup of index $1$or $2$in the group of all Hodge isometries of the twisted K3 surface. We show that both indices can occur.
Generalization, epistemology and concrete: what can social sciences learn from the common sense of engineers
Authors: Tulumello Simone
Published: April 2019

In this essay I debate critically, and somehow playfully, some assumptions and shortcomings of quantitative/positivist social research, using a dash of common sense typical of engineers. Civil engineers, in designing concrete structures, particularly those made up of concrete, have to continuously consider the error embedded in the limits of available systems of calculation, ending up adopting substantial factors of safety as counter-measures. The study of resistance of concrete structures is a good metaphor for social research; and yet, quantitative/positivist researchers, in their search for “falsifiable generalizations”, often forget about the omnipresence of error, let alone adopt the factors of safety. In short, the common sense of engineers is useful to casts some not-so-frequently-considered doubts over the capacity of quantitative methods and positivist epistemologies to create generalizable social science findings in face of uncertainty and the complexity of human societies. By casting such doubts, I advocate for a more relaxed (but not less rigorous) approach to social research and its complexity.
The state of Palestinian youth – commentary to Habashi
Authors: Marshall David J.
Published: April 2019

This reflection is a response to Habashi's article "Palestinian children: a transformation of national identity in the Abbas era." It considers the unique scalar and temporal challenges of researching with Palestinian children in the context of a territorially fractured Palestine.
Understanding (un)certainty in human geographic quantitative spatial analysis – commentary to Tulumello
Authors: Kotavaara Ossi
Published: April 2019

This commentary reflects uncertainty in human geographic quantitative spatial analysis within the context of Simone Tulumello’s essay (in this issue). Epistemologically, positivism, logical empiricism and behaviourism must be understood as historical stages in the evolution of quantitative human geography, even though the analytical legacy is clear. A more recognisable quantitative methodological framework, related to post-millennial human geographic studies, seeks sufficient evidence, which supports or refutes a particular line of thought. In general, the consideration of uncertainty and error is deeply tied to the methodological knowledge in quantitative analysis. Regardless of methodology or discipline, however, the risks of reporting over-certainty or clear misconduct are essential ethical questions. Uncertainty is linked also to the limits of conceptualisation and information catchment, but robust information revealing otherwise-hidden patterns is often highly valuable.
A Temperature Model for Synchronized Ultrasonic Torrefaction and Pelleting of Biomass for Bioenergy Production
Authors: Sun Mingman , Yang Yang , Zhang Meng
Published: April 2019

Low-energy and volumetric density of biomass has been a major challenge, hindering its large-scale utilization as a bioenergy resource. Torrefaction is a thermochemical pretreatment process that can significantly enhance the properties of biomass as a fuel by increasing the heating value and thermal stability of biomass materials. Densification of biomass by pelleting can greatly increase the volumetric density of biomass to improve its handling efficiency. Currently, torrefaction and pelleting are processed separately. So far, there has been little success in dovetailing torrefaction and pelleting, which only requires a single material loading to produce torrefied pellets. Synchronized ultrasonic torrefaction and pelleting has been developed to address this challenge. Synchronized ultrasonic torrefaction and pelleting can produce pellets of high energy and volumetric density in a single step, which tremendously reduces the time and energy consumption compared to that required by the prevailing multistep method. This novel fuel upgrading process can increase the biomass temperature to 473–573 K within tens of seconds to create torrefaction. Studying the temperature distribution is crucial to understand the fuel upgrading mechanism since pellet energy density, thermal stability, volumetric density, and durability are all highly related to temperature. A rheological model was established to instantiate biomass behaviors when undergoing various ultrasonic vibration conditions. Process parameters including ultrasonic amplitude, ultrasonic frequency, and pelleting time were studied to show their effects on temperature at different locations in a pellet. Results indicated that the volumetric heat generation rate was greatly affected by both ultrasonic amplitude and frequency. This model can help to understand the fuel upgrading mechanism in synchronized ultrasonic torrefaction and pelleting and also to give guidelines for process optimization to produce high-quality fuel pellets.
Experimental and Numerical Investigations in a Gas-Fired Boiler With Combustion Stabilizing Device
Authors: Yi Zhengming , Zhou Zheng , Tao Qian , Jiang Zhiwei
Published: April 2019

The combustion stability has a significant influence on safety and reliability of a gas-fired boiler. In this study, a numerical model was first established and validated to investigate the effect of combustion stabilizing device on flow and combustion characteristics of 75 t/h blast furnace gas (BFG) and coke oven gas (COG) mixed-fired boiler. The results indicated that the device coupled with four corner burners enables the flame to spin upward around its side surface, which facilitates heat exchange between BFG and the device. Under stable combustion condition, the combustion stabilizing device can be used as a stable heat source and enhance heat exchange in the furnace. Then, to obtain optimal COG ratio, combustion process of different blending ratios were experimentally investigated. The experimental results revealed that the energy loss due to high exhaust gas temperature is relatively high. COG ratio should be set up taking into account both boiler efficiency and NOX emissions. When COG blending ratio is maintained about 20%, the thermal efficiency of the boiler is 88.84% and the NOX concentration is 152 mg/m3 at 6% O2, meeting NOX emissions standard for the gas boiler.
Damköhler Number Analysis on The Effect of Ozone on Autoignition and Flame Propagation in Internal Combustion Engines
Authors: Keum Seunghwan , Kuo Tang-Wei
Published: April 2019

Ozone-assisted combustion has shown promise in stabilizing combustion and extending operating range of internal combustion engines. However, it has been reported that sensitivity of ozone quantity on combustion varies significantly depending on combustion modes. For example, autoignition-driven combustion in homogeneous charge compression ignition (HCCI) engine was found to be highly sensitive to the ozone concentration, and up to 100 ppm was found to be sufficient to promote combustion. On the other hand, flame propagation in spark-ignition (SI) engine has been reported to be much less sensitive to the ozone amount, requiring ozone concentration about 3000 ∼ 6000 ppm to realize any benefit in the flame speed. A better understanding of the ozone sensitivity is required for combustion device design with ozone addition. In this study, a Damköhler number analysis was performed to analyze the vast difference in the ozone sensitivity between autoignition and flame propagation. The analysis showed that, for ozone to be effective in flame propagation, the contribution of ozone on chemistry should be large enough to overcome the diffused radical from the oxidation layer. It is expected that similar analysis will be applicable to any additives to provide an understanding of their effect.
Fundamental Study of Diesel-Piloted Natural Gas Direct Injection Under Different Operating Conditions
Authors: Fink Georg , Jud Michael , Sattelmayer Thomas
Published: April 2019

Natural gas as an alternative fuel in engine applications substantially reduces both pollutant and greenhouse gas emissions. High pressure dual fuel (HPDF) direct injection of natural gas and diesel pilot has the potential to minimize methane slip from gas engines and increase the fuel flexibility, while retaining the high efficiency of a diesel engine. Speed and load variations as well as various strategies for emission reduction entail a wide range of different operating conditions. The influence of these operating conditions on the ignition and combustion process is investigated on a rapid compression expansion machine (RCEM). By combining simultaneous shadowgraphy (SG) and OH* imaging with heat release rate analysis, an improved understanding of the ignition and combustion process is established. At high temperatures and pressures, the reduced pilot ignition delay and lift-off length minimize the effect of natural gas jet entrainment on pilot mixture formation. A simple geometrical constraint was found to reflect the susceptibility for misfiring. At the same time, natural gas ignition is delayed by the early pilot ignition close to the injector tip. The shape of heat release is only marginally affected by the operating conditions and mainly determined by the degree of premixing at the time of gas jet ignition. Luminescence from the sooting natural gas flame is generally only detected after the flame extends across the whole gas jet at peak heat release rate. Termination of gas injection at this time was confirmed to effectively suppress soot formation, while a strongly sooting pilot seems to intensify soot formation within the natural gas jet.
A Study of Scratch Speed Effects on Ductile–Brittle Transition in Silicon
Authors: Alreja Chirag , Subbiah Sathyan
Published: April 2019

A unique rotational double-taper scratching setup is used to study ductile brittle transitions in single crystal (100) p-type silicon using a conical diamond tool at room temperature and scratching speeds ranging between 0.1 m/s and 0.3 m/s. In such a setup, transition from brittle to ductile occurs twice in a single-tapered scratch, during tool entry and tool exit. A well-defined way to determine critical depth of cut via linear crack density per unit crack length is proposed. The scratches were studied using scanning electron microscopy (morphology) and white light interferometry (depth measurements). A comprehensive study of critical depth of cut, compiled from the literature together with data from this study, with scratching speeds from very low to high shows that critical depth of cut decreases from very low scratch speeds to medium scratch speeds and then increases again at very high scratch speeds. An inference from this study is that diamond turning should be conducted at higher cutting speeds than being undertaken today to make use of larger critical depths of cut.
Benchmark analytical solutions for steady state high frequency broadband sound fields in three rectangular enclosures
Authors: Raudales David , Bliss Donald B. , Michalis Krista A. , Rouse Jerry W. , Franzoni Linda P.
Published: April 2019

Analytical solutions are presented for broadband sound fields in three rectangular enclosures with absorption applied on the floor and ceiling, rigid sidewalls, and a vertically oriented dipole source. The solutions are intended to serve as benchmarks that can be used to assess the performance of broadband techniques, particularly energy-based methods, in a relatively straightforward configuration with precisely specified boundary conditions. A broadband Helmholtz solution is developed using a frequency-by-frequency modal approach to determine the exact band averaged mean-square pressures along spatial trajectories within each enclosure. Due to the specific choice of enclosure configuration and absorption distribution, an approximate specular solution can be obtained through a summation of uncorrelated image sources. Comparisons between the band averaged Helmholtz solution and the uncorrelated image solution reveal excellent agreement for a wide range of absorption levels and improve the understanding of correlation effects in broadband sound fields. A boundary element solution with diffuse boundaries is also presented, which produces consistently higher mean-square pressures in comparison with the specular solution, emphasizing the careful attention that must be placed on correctly modeling reflecting boundary conditions and demonstrating the errors that can result from assuming a Lambertian surface.
Artificial enveloping reverberation for binaural auralization using reciprocal maximum-length sequences
Authors: Xiang Ning , Trivedi Uday , Xie Bosun
Published: April 2019

Binaural auralization through proper room-acoustic simulation can produce a realistic listening experience as if the listener were sitting in a room with spatial perception, including enveloping reverberance. Based on analysis of experimentally measured binaural room-acoustic data, this paper discusses an approach to creating artificial but natural-sounding reverberation for binaural rendering that can be employed in simulating such an environment in an efficient way. Approaches to adjusting the spaciousness of enveloping reverberance within the context of artificially generated reverberation are investigated via hearing tests. This paper exploits the excellent pseudorandom properties of maximum-length sequences to generate deterministic and controllable decorrelations between binaural channels for artificial reverberation for room-acoustic simulations with high computational efficiency. To achieve natural-sounding enveloping reverberance in an enclosed space, and thereby an immersive environment, the shapes of both the reverberation energy decays and the spatial characteristics are found to be decisive. This paper discusses systematic hearing test results that support the mentioned finding.
Diffusion equation modeling for sound energy flow analysis in multi domain structures
Authors: Sü Gül Zühre , Odabaş Erinç , Xiang Ning , Çalışkan Mehmet
Published: April 2019

This study investigates reliable models and methods to be applied in sound field analysis of multi-domain structures. The case structures are two monuments, namely, Süleymaniye Mosque and Hagia Sophia in İstanbul. These are both multi-volume spaces with many smaller sub-volumes coupled to each other by coupling apertures in form of arches. A key concern of the study is to examine energy flow decays and understand the mechanism of multi-slope sound energy decays. The methodology involves diffusion equation model (DEM) application in a finite-element scheme for sound energy flow analysis. Energy flow decays, energy flow dips, and spatial flow vectors are examined for single versus multi-domain DEM solutions. It is concluded that specification of different domains with individual diffusion coefficients is a critical setting such that, if not assigned correctly, may mislead the results. The energy flow vector analysis has enabled us to comprehend the architectural features in relation to such energy flow decay dip occurrence. The computational efficiency of DEM is also discussed. The DEM application in this study has proved to be a powerful and practical method in room acoustics applications, specifically for multi-rate decay investigations.
A mixed boundary condition for accounting energy absorption and transmission in a diffusion equation model
Authors: Navarro Juan M. , Escolano José
Published: April 2019

The acoustic diffusion equation model has shown to be a versatile alternative model for certain types of scenarios where the classical geometrical methods have been demonstrated to be inefficient or even inaccurate. In certain scenarios, the transmission loss plays a fundamental role for accounting, i.e., noise levels and sound propagation between rooms. This paper presents an extension of the absorption boundary conditions known as modified that unifies previously proposed boundary conditions in one equation, including transmission of energy between coupled rooms by both openings and enclosures.
Room acoustics modelling in the time-domain with the nodal discontinuous Galerkin method
Authors: Wang Huiqing , Sihar Indra , Pagán Muñoz Raúl , Hornikx Maarten
Published: April 2019

To solve the linear acoustic equations for room acoustic purposes, the performance of the time-domain nodal discontinuous Galerkin (DG) method is evaluated. A nodal DG method is used for the evaluation of the spatial derivatives, and for the time-integration an explicit multi-stage Runge-Kutta method is adopted. The scheme supports a high order approximation on unstructured meshes. To model frequency-independent real-valued impedance boundary conditions, a formulation based on the plane wave reflection coefficient is proposed. Semi-discrete stability of the scheme is analyzed using the energy method. The performance of the DG method is evaluated for four three-dimensional configurations. The first two cases concern sound propagations in free field and over a flat impedance ground surface. Results show that the solution converges with increasing DG polynomial order and the accuracy of the impedance boundary condition is independent on the incidence angle. The third configuration is a cuboid room with rigid boundaries, for which an analytical solution serves as the reference solution. Finally, DG results for a real room scenario are compared with experimental results. For both room scenarios, results show good agreements.