bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of haemosporidian infections on host survival and recapture rate in the blue tit
Authors: Podmokła Edyta , Dubiec Anna , Drobniak Szymon M. , Sudyka Joanna , Krupski Adam , Arct Aneta , Gustafsson Lars , Cichoń Mariusz
Published: November 2016

Parasites are ubiquitous in the wild and by imposing fitness costs on their hosts they constitute an important selection factor. One of the most common parasites of wild birds arePlasmodiumandHaemoproteus, protozoans inhabiting the blood, which cause avian malaria and malaria‐like disease, respectively. Although they are expected to cause negative effects in infected individuals, in many cases studies in natural populations failed to detect such effect.

Using data from seven breeding seasons (2008–2014), we applied a multistate capture–mark–recapture approach to study the effect of infection with malaria and malaria‐like parasites, individual age and sex on the probability of survival and recapture rate in a small passerine, the blue titCyanistes caeruleus, inhabiting the island of Gotland, Sweden. We found no effect of infection on survival prospects. However, the recapture rate of infected individuals was higher than that of uninfected ones. Thus, while our data do not support the presence of infection costs in terms of host survival, it suggests that parasites from the generaPlasmodiumandHaemoproteusmay affect some aspects of host behaviour, which translates into biased estimation of infection frequency at the population level.
The Life Cycle of Didymium laxifilum and Physarum album on Oat Agar Culture
Authors: Gao Yang , Tao Wei , Yan Shu‐Zhen , Chen Shuang‐Lin
Published: November 2016

The plasmodial slime molds is the largest group in the phylum Amoebozoa. Its life cycle includes the plasmodial trophic stage and the spore‐bearing fruiting bodies. However, only a few species have their complete life cycle known in details so far. This study is the first reporting the morphogenesis of Didymium laxifilum and Physarum album. Spores, from field‐collected sporangia, were incubated into hanging drop cultures for viewing germination and axenic oat agar plates for viewing plasmodial development and sporulation. The spores of D. laxifilum and P. album germinated by method of V‐shape split and minute pore, respectively. The amoeboflagellates, released from spores, were observed in water film. The phaneroplasmodia of two species developed into a number of sporangia by subhypothallic type on oat agar culture. The main interspecific difference of morphogenesis was also discussed.
Reproductive cycle and maternal–embryonic nutritional relationship of shovelnose guitarfish Pseudobatos productus in the Gulf of California
Authors: Romo‐Curiel A. E. , Sosa‐Nishizaki O. , Pérez‐Jiménez J. C. , Rodríguez‐Medrano M. C.
Published: November 2016

Samples of the shovelnose guitarfish Pseudobatos productus were collected on board a vessel and at landings of artisanal commercial fisheries in the Gulf of California from May 2004 to June 2007. Samples of 650 females, 2047 embryos and 484 uterine eggs were examined. The reproductive cycle is annual, ovulation and parturition occur in July, the uterine eggs are in diapause for 9 months (July–March) before an accelerated growth of embryos of 3 months. Histological analyses of the uterine wall of pregnant females suggested that no secretions were used for embryo nourishment. The standard percentage of water content was 48·6% in fertilized eggs and 80·75% in full‐term embryos. Dry mass loss during embryonic development was 16·3% and the chemical balance of development was 0·84. This indicates that P. productus is a strictly lecithotrophic, viviparous species, that makes no maternal contribution of nutrients during embryonic development.
Factors associated with anxiety and depression among patients with implantable cardioverter defibrillator
Authors: Wong Mei Fung Florence
Published: November 2016

Aims and objectives

To identify factors associated with anxiety and depression of patients with implantable cardioverter defibrillators.

Background

Implantable cardioverter defibrillator is effective to increase survival from life‐threatening arrhythmias, but it lowers health‐related quality of life. Anxiety and depression had significant negative association with health‐related quality of life. However, knowledge about factors associated with these two negative emotions in this specific population is inadequate.

Design

A cross‐sectional descriptive design was conducted. Secondary analysis was performed to address the aim.

Methods

A convenience sampling of patients with implantable cardioverter defibrillators was performed. Anxiety and depression were measured by the Hospital Anxiety and Depression Scale through face‐to‐face interview.

Results

Stepwise multivariable regression results showed that older age (aged 60–69 and ≥70: B = 2·08 and 3·31, p = 0·039 and <0·001), self‐care dependence (B = 3·47, p < 0·001), being married (B = −2·21, p = 0·004) and having ischaemic heart disease (B = −1·80, p = 0·008) were significantly associated with depression. However, there was no significant factor associated with anxiety.

Conclusions

Factors associated with depression among patients with implantable cardioverter defibrillator are identified. Older age (aged ≥60) and more self‐care dependence have positive, but being married and having ischaemic heart disease have negative association with depression. Strategies to reduce psychological distress are highlighted.

Relevance to clinical practice

The study findings direct the care to improve health‐related quality of life by reducing and controlling vulnerabilities arising from depression. Patients who are older people (≥aged 60) and more self‐care dependent perceive higher depression. Nursing strategies are suggested to reduce depression especially for those who are older people and more self‐care dependent. Early screening is essential to provide immediate care for reducing vulnerabilities arising from depression. Performing comprehensive assessment for self‐care ability and providing adequate assistance are crucial. Family involvement may reduce depression through providing physical and psychosocial support.
The cardiac patients’ perceptions of their responsibilities in adherence to care: a qualitative interview study
Authors: Kangasniemi Mari , Hirjaba Marina , Kohonen Katja , Vellone Ercole , Moilanen Tanja , Pietilä Anna‐Maija
Published: November 2016

Aims and objectives

To describe cardiac patients’ perceptions of their responsibilities in adherence to care.

Background

The responsibilities of cardiac patients’ adherence to care is a topical issue because of the increasing prevalence of noncommunicable diseases in Western countries, including cardiovascular disease (CVD). Responsibilities for cardiac patients’ care have been studied, but little is described about patients’ perspectives in this study.

Design

A qualitative, hermeneutic inquiry.

Methods

We used face‐to‐face individual semistructured interviews with 21 cardiac patients (76% male) aged 58–86 in an urban area of Finland in winter 2013. The data were analysed hermeneutically with inductive content analysis.

Results

Based on our results, patients with cardiac disease understood that autonomy provided a basis for their responsibility in adherence to care. It included being able to make independent decisions, in collaboration with health professionals, or even to entrust that responsibility to healthcare professionals. Responsibilities were understood to be an expression of adherence, perceived to benefit the patient and included the duty to adopt a healthy lifestyle and care for their own medical condition. The main factors that influenced patients’ responsibilities around adherence to care were their individual resources and motivation, relationships with healthcare professionals and the resources of the healthcare system.

Conclusion

Autonomy is an inherent part of cardiac patients’ adherence to care, but there has been little focus on their responsibilities in the literature. More attention needs to be paid to the healthcare providers’ abilities to support patients’ duties and responsibilities in clinical practice and to future research.
Fighting words? Joning as conflict talk and identity performance among African American preadolescents
Authors: Delfino Jennifer B.
Published: November 2016

This study examines how preadolescent African American students in Washington, D.C., used a linguistic practice called ‘joning,’ a style of verbal play similar to ritual insults, in peer interactions. Sociolinguists have focused on how children socialize each other into vernacular styles appropriate for peer group use but often assume that they disalign with social and linguistic norms for classroom behavior. Drawing from a nine‐month ethnographic study that the author conducted in an after‐school program, this article analyzes the structure and function of joning as a vernacular style of African American Vernacular English and its uses in constructing classroom identities. Joning often facilitated student learning, but it was perceived as a socially and physically risky linguistic practice because of its uses as conflict talk in the local community. Focusing on preadolescence as a key stage of language socialization, this article shows how minority students modify peer‐learned linguistic practices to pursue academic success on their own terms.
Interaction Mindsets, Interactional Behaviors, and L2 Development: An Affective‐Social‐Cognitive Model
Authors: Sato Masatoshi
Published: November 2016

This classroom‐based study explored links among second language (L2) learners’ interaction mindsets, interactional behaviors, and L2 development in the context of peer interaction. While peer interaction research has revealed that certain interactional behaviors (e.g., receiving corrective feedback and engaging in collaborative interaction) assist L2 learning, it is yet unknown why some learners exhibit these interactional behaviors or how learners’ affective states impact their L2 development. The participants were two Grade 10 English as a foreign language classes in Chile (N = 53). Three data sets were collected: (a) interaction mindset data based on pretask interviews with focus groups from each class (n = 10); (b) interaction data pertaining to the communicative tasks of the focus groups; and (c) L2 development data from both classes consisting of oral and written production tests focusing on grammar and lexis. Results indicated that L2 development was mediated by learners’ interaction mindsets, which in turn affected their interactional behaviors.

Open Practices

This article has been awarded an Open Materials badge. All materials are publicly accessible in the IRIS digital repository at http://www.iris-database.org. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki.
The strikethrough: an approach to regulatory writing and professional discipline
Authors: Jacob Marie-Andrée
Published: November 2016

This paper attends to writing practices by way of examining how a professional regulator engages with research activities conducted by doctors. In order to explore regulatory responses to alleged research misconduct, I use a specific calligraphic practice shared by researchers and regulators. The paper shows that taking this calligraphic practice as an analytical focus can offer surprising dividends to the study of regulation across fields. Via the practice of strikethrough, the General Medical Council effectuates three gestures as it engages with research activities: display, authentication and isolation. Understanding them requires asking what literal and metaphorical meanings travel in the strikethrough.
A comparative study of three extraction protocols of DNA from nails: Potential use in the diagnosis of onychomycoses
Authors: Kotrotsiou T. , Chatzimichaloglou A. , Nasr A. , Spandou E. , Patsatsi A. , Sotiriadis D. , Vyzantiadis T.‐A.
Published: November 2016

Molecular techniques can be useful adjuncts to the diagnosis of onychomycoses. However, the nail presents difficulties in the extraction of its DNA. The comparison of three extraction protocols of DNA from nails and their ranking for possible use in the molecular diagnosis of onychomycoses are described. Extraction was performed on weighed nail clippings of equal size from positive (31) or negative (14) samples, according to the culture result. At Prot1, the extraction was performed according to Tahir and Watson, with an additional step implementing silica columns. At Prot2, the methodology proposed by the Statens Serum Institute of Copenhagen was used. At Prot3, DNA was extracted by the use of magnetic separation after homogenisation with glass beading. The evaluation parameters were DNA purity, DNA concentration, total DNA yield/g of tissue, cost and duration. The multiples of the means of medians of the first three parameters, for each protocol, were calculated. Prot3 showed the highest DNA purity. Prot2 presented the highest DNA concentration and DNA yield/g of tissue, while it was the cheapest and shortest. In total, the three protocols were graded as Prot2>Prot1>Prot3. The second method, although had a lower DNA purity, presented the higher DNA concentration and DNA yield, while its duration and cost were also favourable.
Primary effusion lymphoma involving cerebrospinal fluid, deep cervical lymph nodes and adenoids. Report of a case supporting the lymphatic connection between brain and lymph nodes
Authors: Santonja Carlos , Medina‐Puente Camino , Serrano del Castillo Cristina , Cabello Úbeda Alfonso , Rodríguez‐Pinilla Socorro María
Published: November 2016

We describe an unusual presentation of primary effusion lymphoma in CSF of a 45‐year‐old HIV‐positive man, with no evidence of involvement of pleural, peritoneal or pericardial cavities. Cytologic examination and flow cytometric analysis suggested the diagnosis, eventually made in an excised deep cervical lymph node, in which the neoplastic cells involved selectively the sinuses. This case represents the fifth reported example of CSF involvement by this type of lymphoma, and supports the alleged connection between CSF and cervical lymph nodes via lymphatic vessels. Interestingly, review of an adenoidectomy specimen obtained 9 months before presentation for nonspecific complaints showed rare clusters of neoplastic cells involving surface epithelium and chorium, a finding that might represent a homing mechanism and implies an asymptomatic, occult phase of lymphoma development.
Transcriptomic variation among six Arabidopsis thaliana accessions identified several novel genes controlling aluminium tolerance
Authors: Kusunoki Kazutaka , Nakano Yuki , Tanaka Keisuke , Sakata Yoichi , Koyama Hiroyuki , Kobayashi Yuriko
Published: November 2016

Differences in the expression levels of aluminium (Al) tolerance genes are a known determinant of Al tolerance among plant varieties. We combined transcriptomic analysis of six Arabidopsis thaliana accessions with contrasting Al tolerance and a reverse genetic approach to identify Al‐tolerance genes responsible for differences in Al tolerance between accession groups. Gene expression variation increased in the signal transduction process under Al stress and in growth‐related processes in the absence of stress. Co‐expression analysis and promoter single nucleotide polymorphism searching suggested that both trans‐acting polymorphisms of Al signal transduction pathway and cis‐acting polymorphisms in the promoter sequences caused the variations in gene expression associated with Al tolerance. Compared with the wild type, Al sensitivity increased in T‐DNA knockout (KO) lines for five genes, including TARGET OF AVRB OPERATION1 (TAO1) and an unannotated gene (At5g22530). These were identified from 53 Al‐inducible genes showing significantly higher expression in tolerant accessions than in sensitive accessions. These results indicate that the difference in transcriptional signalling is partly associated with the natural variation in Al tolerance in Arabidopsis. Our study also demonstrates the feasibility of comparative transcriptome analysis by using natural genetic variation for the identification of genes responsible for Al stress tolerance.
Studying Incremental Institutional Change: A Systematic and Critical Meta‐Review of the Literature from 2005 to 2015
Authors: van der Heijden Jeroen , Kuhlmann Johanna
Published: November 2016

Since the early 2000s, theorizing on incremental institutional change has made inroads in comparative historical analysis. In particular, the ideas, concepts, and theory introduced by Kathleen Thelen and her collaborators have been widely adopted by scholars. These scholars are not, however, univocally positive about the theory. Three main critiques have been plaguing the theory since its early days: the concepts it builds on lack clarity, the model of agency it uses is too static, and the theory lacks analytical power overall. Following the Preferred Reporting Items for Systematic Reviews and Meta‐Analysis method, this article presents a meta‐analysis of the peer‐reviewed empirical literature from 2005 to 2015 that applies this theory. It seeks to better understand the reach of the critiques expressed, as this may provide a starting point for improvement. It finds considerable quantitative support for the critiques, and uncovers an additional problematic issue: the tendency for concept stretching and concept proliferation by scholars seeking to overcome the shortcomings of the theory. Paradoxically, concept stretching and proliferation only further reduce the analytical power of the theory. The article concludes with suggestions for improvement of the development and application of the theory.
Symbolic Racism, Institutional Bias, and Welfare Drug Testing Legislation: Racial Biases Matter
Authors: Ledford Chris
Published: November 2016

Since the devolution of welfare policymaking to the states after the passage of the 1996 Personal Responsibility and Work Opportunity Reconciliation Act, there has been contentious debate about drug testing welfare applicants. Beyond elite rhetoric and debate points about the implications of welfare drug testing, extant research remains limited insofar as providing theoretical understanding about what factors influence state proposal of legislation requiring welfare applicants to submit to drug tests. I develop and test expectations that derive from research on welfare attitudes, social construction theory, and policy design—specifically, hypotheses that the proportion of blacks on state temporary assistance for needy families caseloads, as well as state‐aggregate levels of symbolic racism, significantly influence state proposal of drug testing legislation. My multilevel analysis of every state proposal of welfare drug testing legislation from 2008 to 2014 yields strong evidence in support of these hypotheses and paints a more complete picture of the influence of racial attitudes on state welfare policymaking. Specifically, while much research finds evidence of institutional racial biases in the implementation of welfare policy, the evidence presented herein shows that these biases, as well as public biases, influence policymaking at the proposal stage. Implications of these findings are discussed in light of recent significant electoral gains made by Republicans in state legislatures.
Association between asthma control and asthma cost: Results from a longitudinal study in a primary care setting
Authors: Nguyen Hai V. , Nadkarni Nivedita V. , Sankari Usha , Mital Shweta , Lye Weng K. , Tan Ngiap C.
Published: November 2016

ABSTRACT

Background and objective

Asthma control can be assessed with the Asthma Control Test (ACT) and a score of 20 or higher indicates good asthma control. Patients pay for their consultation and treatment in the fee‐for‐service primary healthcare system in Singapore. We hypothesized that achieving asthma control would result in lower asthma costs through reduced acute exacerbations, fewer physician consultations and lower lost productivity. The study compared the healthcare costs of patients who achieved asthma control and those with suboptimal asthma control based on ACT scores. Factors influencing asthma control and healthcare expenditure over time were also examined.

Methods

A total of 736 patients were enrolled into an asthma care programme in two polyclinics during 2008 and 2013. Direct costs of asthma management were derived from the frequency of polyclinic consultations, medication costs and hospitalization. Indirect costs were estimated from lost workdays due to exacerbations. The generalized estimating equation (GEE) approach was used to longitudinally model the factors associated with total healthcare expenditure.

Results

Patients with asthma control spent S$48 (US$36) more per doctor visit on asthma drugs (P < 0.01) but incurred S$65 (US$48) less per doctor visit in total costs (P < 0.01) than those with suboptimal asthma control. The savings from achieving asthma control for obese patients were greater than for normal‐weight patients (S$42 or the equivalent of US$31; P < 0.05).

Conclusion

Optimal asthma control was associated with reduced healthcare costs. An effective treatment regimen should also consider other modifiable factors such as weight control to achieve asthma control and eventually reduce asthma costs.
Application of Graph Theory to Cost‐Effective Fire Protection of Chemical Plants During Domino Effects
Authors: Khakzad Nima , Landucci Gabriele , Reniers Genserik
Published: November 2016

In the present study, we have introduced a methodology based on graph theory and multicriteria decision analysis for cost‐effective fire protection of chemical plants subject to fire‐induced domino effects. By modeling domino effects in chemical plants as a directed graph, the graph centrality measures such as out‐closeness and betweenness scores can be used to identify the installations playing a key role in initiating and propagating potential domino effects. It is demonstrated that active fire protection of installations with the highest out‐closeness score and passive fire protection of installations with the highest betweenness score are the most effective strategies for reducing the vulnerability of chemical plants to fire‐induced domino effects. We have employed a dynamic graph analysis to investigate the impact of both the availability and the degradation of fire protection measures over time on the vulnerability of chemical plants. The results obtained from the graph analysis can further be prioritized using multicriteria decision analysis techniques such as the method of reference point to find the most cost‐effective fire protection strategy.
A Bayesian Model and Stochastic Exposure (Dose) Estimation for Relative Exposure Risk Comparison Involving Asbestos‐Containing Dropped Ceiling Panel Installation and Maintenance Tasks
Authors: Boelter Fred W. , Xia Yulin , Persky Jacob D.
Published: November 2016

Assessing exposures to hazards in order to characterize risk is at the core of occupational hygiene. Our study examined dropped ceiling systems commonly used in schools and commercial buildings and lay‐in ceiling panels that may have contained asbestos prior to the mid to late 1970s. However, most ceiling panels and tiles do not contain asbestos. Since asbestos risk relates to dose, we estimated the distribution of eight‐hour TWA concentrations and one‐year exposures (a one‐year dose equivalent) to asbestos fibers (asbestos f/cc‐years) for five groups of workers who may encounter dropped ceilings: specialists, generalists, maintenance workers, nonprofessional do‐it‐yourself (DIY) persons, and other tradespersons who are bystanders to ceiling work. Concentration data (asbestos f/cc) were obtained through two exposure assessment studies in the field and one chamber study. Bayesian and stochastic models were applied to estimate distributions of eight‐hour TWAs and annual exposures (dose). The eight‐hour TWAs for all work categories were below current and historic occupational exposure limits (OELs). Exposures to asbestos fibers from dropped ceiling work would be categorized as “highly controlled” for maintenance workers and “well controlled” for remaining work categories, according to the American Industrial Hygiene Association exposure control rating system. Annual exposures (dose) were found to be greatest for specialists, followed by maintenance workers, generalists, bystanders, and DIY. On a comparative basis, modeled dose and thus risk from dropped ceilings for all work categories were orders of magnitude lower than published exposures for other sources of banned friable asbestos‐containing building material commonly encountered in construction trades.
Treating the Capability for Suicide: A Vital and Understudied Frontier in Suicide Prevention
Authors: Anestis Michael D. , Law Keyne C. , Jin Hyejin , Houtsma Claire , Khazem Lauren R. , Assavedo Brittney L.
Published: November 2016

Current efforts at suicide prevention center largely on reducing suicidal desire among individuals hospitalized for suicidality or being treated for related psychopathology. Such efforts have yielded evidence‐based treatments, and yet the national suicide rate has continued to climb. We propose that this disconnect is heavily influenced by an unmet need to consider population‐level interventions aimed at reducing the capability for suicide. Drawing on lessons learned from other public health phenomena that have seen drastic declines in frequency in recent decades (HIV, lung cancer, motor vehicle accidents), we propose that current suicidality treatment efforts trail current suicidality theories in their lack of focus on the extent to which individuals thinking about suicide are capable of transitioning from ideation to attempt. We summarize extant evidence for specific capability‐centered approaches (e.g., means safety) and propose other options for improving our ability to address this largely overlooked variable. We also note that population‐level approaches in this regard would represent an important opportunity to decrease risk in individuals who either lack access to evidence‐based care or underreport suicidal ideation, as a reduced capability for suicide would theoretically diminish the potency of suicidal desire and, in this sense, lower the odds of a transition from ideation to attempt.
Characterisation of maternal human leukocyte antigen class I antibodies in suspected foetal and neonatal alloimmune thrombocytopenia
Authors: Refsum E. , Mörtberg A. , Dahl J. , Meinke S. , Auvinen M.‐K. , Westgren M. , Reilly M. , Höglund P. , Wikman A.
Published: November 2016

Objectives

To investigate the specificities and level of HLA class I antibodies in selected cases referred for suspected foetal and neonatal alloimmune thrombocytopenia (FNAIT).

Background

FNAIT occurs in 1 : 1–2000 live births, whereas maternal immunisation against human leukocyte antigen (HLA) class I is common. Whether HLA class I antibodies alone can cause FNAIT is debatable.

Material and methods

A total of 260 patient samples were referred between 2007 and 2012. Referrals with maternal HLA class I antibodies and no other cause for the neonatal thrombocytopenia were included for analysis (cases, n = 23). HPA‐1a negative mothers were excluded. Control groups were screened positive mothers of healthy neonates (controls, n = 33) and female blood donors (blood donors, n = 19). LABScreen single antigen HLA class I beads was used for antibody analysis. Clinical records were reviewed for cases.

Results

All groups had broad antibody reactivity. Cases had more antibodies with high SFI levels compared with the controls (SFI>9999; medians 26, 6 and 0; P < 0·05) and higher overall median HLA‐ABC and HLA‐B SFI (P < 0·05). Many of the antibodies were reactive with rare alleles. When reviewing the clinical records, several of the cases had other contributing factors to the thrombocytopenia. There was no correlation between foetal platelet count and antibody levels.

Conclusion

Mothers of thrombocytopenic neonates had higher levels of HLA class I antibodies compared with control groups of women with healthy children and female blood donors. However, clinical outcome and antibody response correlated poorly in the heterogeneous case group, indicating a multifactorial cause to the thrombocytopenia in the majority of cases.
Controlling Rumex obtusifolius by means of hot water
Authors: Latsch R , Anken T , Herzog C , Sauter J
Published: November 2016

Hot‐water treatment of broad‐leaved dock (Rumex obtusifolius) was developed as an alternative to manual digging out in organic farming. During treatment, the top region of the root was heated so that the plants would die back. The aim of this study was to validate the efficacy of the hot‐water treatment of dock roots. The trials were carried out with a commercially available hot‐water high‐pressure cleaner and a rotating nozzle for water application. The target plant control rate assessed 12 weeks after treatment was set at >80%. The appraisal covered 1330 treated plants of varying size from four sites with three different soil texture classes. Parameters which influenced the control rate were water temperature, amount of water, soil moisture and soil texture. Additional parameters recorded were the amount of fuel oil consumption and working time requirements. A reassessment of the plants 1 year after treatment yielded information concerning the ground cover, the possible germination of new dock plants from buried seeds and the soil structure of the site treated. In order to achieve the target control rate of >80%, it is recommended that the temperature of the water leaving the equipment should exceed 80°C. The amount of water required depends on root size and soil moisture. On average, 131 plants per hour can be treated with no negative effects on regrowth or soil structure. Hot‐water treatment is the first functional control alternative to manual digging out R. obtusifolius for organic farming.
Effect of Local Thermal Nonequilibrium on the Stability of Natural Convection in an Oldroyd-B Fluid Saturated Vertical Porous Layer
Authors: Shankar B. M. , Shivakumara I. S.
Published: November 2016

The effect of local thermal nonequilibrium (LTNE) on the stability of natural convection in a vertical porous slab saturated by an Oldroyd-B fluid is investigated. The vertical walls of the slab are impermeable and maintained at constant but different temperatures. A two-field model that represents the fluid and solid phase temperature fields separately is used for heat transport equation. The resulting stability eigenvalue problem is solved numerically using Chebyshev collocation method as the energy stability analysis becomes ineffective in deciding the stability of the system. Despite the basic state remains the same for Newtonian and viscoelastic fluids, it is observed that the base flow is unstable for viscoelastic fluids and this result is qualitatively different from Newtonian fluids. The results for Maxwell fluid are delineated as a particular case from the present study. It is found that the viscoelasticity has both stabilizing and destabilizing influence on the flow. Increase in the value of interphase heat transfer coefficient Ht, strain retardation parameter Λ2 and diffusivity ratio α portray stabilizing influence on the system while increasing stress relaxation parameter Λ1 and porosity-modified conductivity ratio γ exhibit an opposite trend.
Acoustic Damper Placement and Tuning for Annular Combustors: An Adjoint-Based Optimization Study
Authors: Mensah Georg A. , Moeck Jonas P.
Published: November 2016

Thermoacoustic instabilities pose a major threat to modern gas turbines. The use of acoustic dampers, like Helmholtz resonators, has proven useful for the mitigation of such instabilities. However, assessing the effect of acoustic dampers on thermoacoustic modes in annular combustion chambers remains an intricate task. This results from the implicit nature of the thermoacoustic Helmholtz equation associated with the high number of possible parameter values for the positioning of the dampers and their impedance design. In the present work, the principal challenges of the effective placement and the design of the impedance of acoustic dampers in annular chambers are discussed. This includes the choice of an appropriate objective function for the optimization, the combinatorial challenges when dealing with different possible damper arrangements, and the numerical complexities when using the thermoacoustic Helmholtz equation to approach this issue. As a key aspect, the paper proposes a new adjoint-based approach to tackle these problems. The new algorithm establishes algebraic models that predict the effect of acoustic dampers on the growth rates of the thermoacoustic modes. The theory is exemplified on the basis of a generic annular combustor model with 12 burners.
Self-Excited Vibration of a Flexibly Supported Shafting System Induced by Friction
Authors: Qin Wenyuan , Zhang Zhenguo , Qin Hui , Zhang Zhiyi
Published: November 2016

Self-excited vibration of a flexibly supported shafting system in a gravity water tunnel was observed in the testing of friction of water-lubricated rubber bearings. The measured vibrations indicated that the self-excited vibration, characterized by a single-mode vibration modulated by the shaft speed, emerged at a specific speed and grew stronger as the shaft speed decreased, but it would cease at a very low-speed. To explain the mechanism of instability, a dynamic model of the system was built. The substructure synthesis method was employed to model the dynamics of the shafting system, which was divided into two subsystems: the flexible support and the shaft. Before the synthesis, natural frequencies and modes of the subsystems were computed by the finite element method. According to the modal parameters and connecting conditions, a synthesized model was built to take into account the friction between the shaft and the bearing. The fourth-order Runge–Kutta method was used to solve the dynamic equations, and the influences of physical parameters on vibration stability were analyzed. The results have shown that certain vibration modes of the flexible support tend to be unstable under the excitation of the friction. Both the simulation and experimental results have exhibited that the unstable modes are associated with the torsional vibration of the flexible support, which are in fact lightly damped and accordingly can be easily excited by the circumferential friction. Therefore, the coupling between the torsional vibration of the flexible support and the friction of the water-lubricated rubber bearing is the main factor leading to the vibration instability.
Risk-Based Mitigation of Mechanical Damage
Authors: Ma Jing , Zhang Fan , Desjardins Guy
Published: November 2016

According to the PHMSA data on reportable incidents, for the 20 years ranging from 1995 to 2014, excavation damage accounted for 16.4% of the incidents on 301,732 miles of gas transmission pipelines and 15.6% of the incidents on 199,210 miles of hazardous liquid pipelines. On the whole, excavation damage is a major cause of incidents, ranking third following incidents caused by material/weld/equipment failure and corrosion.

For the purposes of this study, mechanical damage is separated into two categories, i.e. immediate failures and delayed failures. An immediate failure is one which occurs at the instant the damage is done to the pipeline. A puncture, for example, is an immediate failure. Delayed failures involve damage that is not sufficient to cause a leak or a rupture at the time it is inflicted. On average, 14.6% of the mechanical damage incidents in gas transmission pipelines and 13.3% of the mechanical damage incidents in hazardous liquid pipelines can be classified as delayed failures.

The immediate failures are generally minimized through the preventative measure and design efforts. For instance, it is shown herein that the puncture probability can be calculated through the comparison between the likelihood of any given external load being imposed and inherent pipe resistance.

While preventative measures serve to reduce the occurrences of delayed failures as well as the occurrences of immediate failures, delayed failures are largely mitigated through in-line inspection and timely remediation actions. The fact that the assessment methods for mechanical damage are generally not as robust as those for cracks and corrosion tends to limit the reliability of deterministic calculations of response times. Therefore, in the study described herein, risk-based approaches to minimizing delayed failures were developed. Three different approaches to deciding which dents need to be excavated after an ILI were pursued. One involves the use of reportable incident rates based on the PHMSA statistics in conjunction with the number of ILI dent indications per mile to get a probability of failure. The second consists of a decision-making process based on the ILI-reported dent depths and the dent fatigue life probability-of-exceedance function. The third relates to a decision-making process based on successive excavations of dents located by ILI, in which the Bayesian method is applied to compare predicted versus actual severity and thereby determine the probability of failure associated with stopping after a specific number of excavations.
CTOA Test Method Using Drop-Weight Tear Test (DWTT): Background and Development of Standard
Authors: Xu S. , Tyson W. R. , Simha C. H. M. , Gesing M. , Liang J.
Published: November 2016

Arrest of fast ductile fracture in the design of gas pipelines has traditionally been assured by specifying Charpy absorbed energy (Cv) of pipe steel based on the Battelle two-curve method. However, the Charpy test has been shown to be inadequate to characterize crack propagation in modern high-strength, high-toughness pipe steels. For steels with Cv more than approximately 100 J, fracture arrest methodologies based on Cv can lead to non-conservative predictions. The problem is that the Charpy specimen is too small to characterize full-scale fracture, and for tough steels the ductility can be so high that the Charpy specimen bends without fracturing completely. To overcome these limitations, the use of a larger full-thickness specimen, the “Drop-Weight Tear Test” (DWTT) specimen, has been proposed. The test is instrumented to measure the force on and displacement of the impactor during crack propagation. The data is interpreted to yield the “crack-tip opening angle” (CTOA), which is constant during steady-state crack growth and characterizes the propagation resistance. The CTOA has been proposed for some time as a suitable property to assess fracture propagation and arrest in high-pressure gas pipelines, but up to now a standard test method for measurement of the CTOA has not been available. To remedy this situation, a draft standard has been developed by the authors and is being balloted by ASTM E081.

In this paper, the CTOA parameter and CTOA-based fracture arrest methodology will be introduced briefly. The background and development of the draft ASTM standard test method for determination of CTOA using the drop-weight tear test (DWTT) specimen will be reviewed including the procedure and the results of an international round robin. In the CTOA test method, the only adjustable parameter is the rotation factor (rp). Using a modified Xue-Wierzbicki damage mechanics model and a statistical analysis, rp has been determined to be a weak function of yield strength, Charpy absorbed energy and specimen thickness. Although no physical model has been developed to explain the interplay of these factors, they are all related to the extent and distribution of plastic deformation ahead of the crack. The technical background and quantification of rp will be described in this paper. It is intended to apply the CTOA test method to a broad range of steels, including thin (less than 6 mm) and thick (larger than 20 mm) pipe steels.
Identifying and Sizing Axial Seam Weld Flaws in ERW Pipe Seams and SCC in the Pipe Body Using Ultrasonic Imaging
Authors: Haines Harvey , Hörchens Lars , Tomar Pushpendra
Published: November 2016

A significant portion of the global energy pipeline infrastructure is constructed with pipe materials manufactured using the Electric Resistance Weld (ERW) process. The longitudinal seam of these ERW pipelines may contain manufacturing flaws and anomalies that can grow over time through pressure cycle fatigue and result in a pipeline integrity failure. These flaws/anomalies can be present in both vintage pipe (generally pre-1970) manufactured using a low frequency ERW process and more modern pipe that is manufactured using a high frequency ERW process. ERW seam anomalies are challenging to detect, discriminate, and size with current In-Line Inspection and In-Ditch NDE inspection technologies, which is driving the industry to better understand current inspection industry performance and to develop new technologies for ERW seam anomaly inspection.

Ultrasonic (UT) imaging using inverse wave field extrapolation (IWEX) is an emerging NDE technique that is being applied to improve discrimination and sizing of anomalies in pipelines. This paper will describe the IWEX development, the challenges related to seam weld integrity and assessment and SCC assessment, and results from studies to evaluate performance. Ultrasonic imaging is also compared to the current state-of-the-art techniques such as ultrasonic phased array (PA). A goal of the project is to produce images capable of discriminating cold welds, surface breaking hook cracks, non-surface breaking upturned fiber indications, poor trim, offset plate edges, and anomalies with fatigue cracking. The goal is to size all of the cracks in a SCC colony and produce a three-dimensional map of the area. In mapping these anomalies the sizing needs to be sufficiently accurate to qualify in-line inspection tools used for crack inspection.
Effect of Crack Depth on Burst Strength of X70 Linepipe With Dent-Crack Defect
Authors: Ghaednia Hossein , Das Sreekanta , Zohrehheydariha Jamshid , Wang Rick , Kania Richard
Published: November 2016

External interferences cause various defects, which significantly affect the transportation of oil and gas in pipelines. Corrosion, crack, puncture, dent, gouge, and combination of such damages from a variety of external interferences are some common examples of surface damage in pipelines. Gouges, dents, cracks, and punctures that form in the pipe wall as a result of contact and/or impact from foreign objects are often referred to as mechanical damage. Structural integrity of oil and gas transmission pipelines is often threatened by these mechanical damages and as a result, a failure of the pipeline may occur. A defect that contains both dent and crack, often known as dent-crack defect, may lead to a rupture or leak in the pipe wall. This kind of defect is a matter of serious concern for the pipeline operator since a rupture or a leak may occur. Hence, an experimental study was completed at the Centre for Engineering Research in Pipelines (CERP), University of Windsor on 30 inch (762 mm) diameter and X70 grade pipes with D/t of 90. This project was undertaken through laboratory based experimental work and numerical study using non-linear finite element analysis (FEA) method. The purpose of full-scale test was to collect test data to be able to validate finite element (FE) model. The validated FE model was then used to undertake parametric study for determining the effect of the crack depth and operating (internal) pressure on the burst strength of NPS30 X70 grade oil and gas pipe. The parameters chosen in the FE based parametric study are: (1) crack depth which was varied from 0.25 to 0.75 of pipe wall thickness and (2) internal pressure applied during denting process (operating pressure of linepipe) was varied from no internal pressure to 0.75py. This study found that the dent-crack defect with crack depth of 75% of wall thickness could reduce the pressure capacity by 54%.
Findings From an Investigation of Hydrotest Protocols
Authors: Olson Richard J. , Young Bruce A. , Leis Brian
Published: November 2016

Experience has shown that in-service failures can occur in Electric Resistance Welded (ERW) line pipe shortly after a hydrotest as a part of line rehabilitation or in retesting to return to service. This can occur due to near-critical features that grew but remained in the line, or due to a pressure-reversal due to stable defect growth during the pressure test. The objective of this study was to improve hydrotesting protocols by developing and optimizing procedures for conducting hydrotests of pipe with ERW or Flash Welded (FW) seam defects, and validating the practical utility of the proposed procedures.

This work has enhanced and adapted both failure and growth models to predict the behavior of defect shapes based on collapse and fracture theories, to assess idealized cold welds, hook cracks, and selective-seam weld corrosion (SSWC), and parametrically quantify differences and similarities in their response to increasing pressure. Based on insight from these analyses, this work has established a pressure-time sequence that incorporates the spike concept to expose near-critical defects to pressures that will cause them to fail and it has evaluated the sensitivity as a function of defect size with respect to time-dependent growth. In turn, insights from the outcomes of these analyses were used to identify potential hydrotest protocols.
Development of Grade X80 High Charpy Energy Linepipe by MA Formation Control
Authors: Kimura Hideyuki , Yokota Tomoyuki , Ishikawa Nobuyuki , Kakihara Shinichi , Kondo Joe
Published: November 2016

Higher grade linepipes such as grade X80 have been developed and applied to long distance pipelines in order to reduce the cost of pipeline construction by using thinner pipes than is possible with conventional grades. Service pressures have also been increased in recent years for efficient gas transportation. In addition to the requirement of higher strength, running ductile fracture should be prevented in long distance and high pressure pipelines. Resistance to ductile fracture, as evaluated by Charpy energy, is an important material property for higher grade linepipes.

It has been reported that bainite single-phase steel tends to show higher Charpy energy than ferrite-bainite or bainite-MA (martensite-austenite constituent) dual-phase steels, since void nucleation is suppressed in single-phase steels compared with dual-phase steels. However, in higher grade steels with a bainite single phase, a small amount of MA grains generally remains due to the chemical stability of MA. Therefore, further reduction of MA is key to improving Charpy energy for higher grade linepipe steels. In order to achieve high Charpy energy by MA formation control, the optimum conditions of the plate manufacturing process were investigated. As a result, a high Charpy energy was achieved by the combination of controlled rolling and precise control of the accelerated cooling conditions, by which the MA phase was minimized.

Based on the above investigation, grade X80 high Charpy energy linepipes were trial-produced by applying JFE Steel’s optimized accelerated cooling (ACC) system with a high cooling rate and homogeneous temperature profile. Stable higher Charpy energy was achieved by minimizing MA formation and achieving a homogeneous microstructure by advanced cooling control.