bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic conditions in children increase the risk for physical abuse – but vary with socio‐economic circumstances
Authors: Svensson Birgitta , Bornehag Carl‐Gustaf , Janson Staffan
Published: September 2010

Aim:  To explore whether children (age 10, 12 and 15 years) with self‐reported chronic conditions are at higher risk of physical abuse and/or exposure to intimate‐partner violence than other children, while considering the importance of demographic factors.

Methods:  A national cross‐sectional study of 2771 pupils in grades 4, 6 and 9 from 44 schools in Sweden (91% response rate). Conflict Tactic Scales were used to measure physical abuse and separate questions measured exposure to intimate‐partner violence. A list of 13 diagnoses was used to estimate chronic conditions.

Results:  Children with chronic conditions had an increased risk for physical abuse (CPA) only (OR 1.67) as well as in combination with exposure to intimate‐partner violence (IPV) (OR 2.54), but not to IPV only, compared to children without chronic conditions. Furthermore, when chronic conditions were combined with country of birth other than Sweden and living in low‐income areas, the risk for CPA increased even more, indicating interactive effects.

Conclusions:  A wide range of chronic health conditions in children increased the risk for physical abuse. This indicates that certain factors unite this group of children, irrespective of the type of disability or degree of severity, but where a combination with socio‐economic circumstances is of importance.
Nerve dysfunction following surgical treatment of cervical non‐tuberculous mycobacterial lymphadenitis in children
Authors: Claesson Gösta , Bennet Rutger , Eriksson Margareta , Petrini Björn
Published: September 2010

Aim:  To present our experience of nerve dysfunction following surgical treatment among 126 children with microbiologically verified non‐tuberculous mycobacterial (NTM) lymphadenitis.

Methods:  We retrieved data from medical records, and a questionnaire with an invitation to a clinical follow‐up was returned by 88 families.

Results:  The time from onset of symptoms to diagnosis was more than 3 months in 24% of subjects. Mycobacterium avium complex was isolated from 105, Mycobacterium malmoense from 12 and Mycobacterium scrofulaceum from one cervical lymph node. A total of 89% of the children underwent surgery and were examined in particular with regard to cranial motor nerve functions. Major persisting nerve dysfunction occurred in 3/51 (6%) children who underwent radical surgery, and minor dysfunction in seven (14%). In nine children, the marginal mandibular branch of the facial nerve was affected, and the accessory nerve was affected in one child. There were no neurological signs in 25 children treated with incision and drainage alone or in 12 followed with observation alone. Healing took >6 months in 2/76 (3%) surgically treated and 3/12 (25%) non‐surgically treated children.

Conclusion:  Considering the risk of nerve dysfunction following extirpation, incision with drainage and observation alone should both be included among the management options for cervical NTM lymphadenitis in children.
Active and regulatory sites of cytosolic 5′‐nucleotidase
Authors: Pesi Rossana , Allegrini Simone , Careddu Maria Giovanna , Filoni Daniela Nicole , Camici Marcella , Tozzi Maria Grazia
Published: September 2010

Cytosolic 5′‐nucleotidase (cN‐II), which acts preferentially on 6‐hydroxypurine nucleotides, is essential for the survival of several cell types. cN‐II catalyses both the hydrolysis of nucleotides and transfer of their phosphate moiety to a nucleoside acceptor through formation of a covalent phospho‐intermediate. Both activities are regulated by a number of phosphorylated compounds, such as diadenosine tetraphosphate (Ap4A), ADP, ATP, 2,3‐bisphosphoglycerate (BPG) and phosphate. On the basis of a partial crystal structure of cN‐II, we mutated two residues located in the active site, Y55 and T56. We ascertained that the ability to catalyse the transfer of phosphate depends on the presence of a bulky residue in the active site very close to the aspartate residue that forms the covalent phospho‐intermediate. The molecular model indicates two possible sites at which adenylic compounds may interact. We mutated three residues that mediate interaction in the first activation site (R144, N154, I152) and three in the second (F127, M436 and H428), and found that Ap4A and ADP interact with the same site, but the sites for ATP and BPG remain uncertain. The structural model indicates that cN‐II is a homotetrameric protein that results from interaction through a specific interface B of two identical dimers that have arisen from interaction of two identical subunits through interface A. Point mutations in the two interfaces and gel‐filtration experiments indicated that the dimer is the smallest active oligomerization state. Finally, gel‐filtration and light‐scattering experiments demonstrated that the native enzyme exists as a tetramer, and no further oligomerization is required for enzyme activation.

Structured digital abstract

 MINT‐8011572: cN‐II (uniprotkb:O46411) and cN‐II (uniprotkb:O46411) bind (MI:0407) by dynamic light scattering (MI:0038)

 MINT‐8011493, MINT‐8011481: cN‐II (uniprotkb:O46411) and cN‐II (uniprotkb:O46411) bind (MI:0407) by molecular sieving (MI:0071)
Wisely chosen paths – regulation of rRNA synthesis
Authors: Grummt Ingrid
Published: September 2010

All cells, from prokaryotes to vertebrates, synthesize enormous amounts of rRNA to produce 1–2 million ribosomes per cell cycle, which are required to maintain the protein synthesis capacity of the daughter cells. In recent years, considerable progress has been made in the elucidation of the basic principles of transcriptional regulation and the pathways that adapt cellular rRNA synthesis to metabolic activity, a process that is essential for understanding the link between nucleolar activity, cell growth, proliferation, and apoptosis. I will survey our present knowledge of the highly coordinated networks that regulate transcription by RNA polymerase I, coordinating rRNA gene transcription and ribosome production with environmental cues. Moreover, I will discuss the epigenetic mechanisms that control the chromatin structure and transcriptional activity of rRNA genes, in particular the role of noncoding RNA in DNA methylation and transcriptional silencing.
Proteolytic processing regulates pathological accumulation in dentatorubral‐pallidoluysian atrophy
Authors: Suzuki Yasuyo , Nakayama Kimiko , Hashimoto Naohiro , Yazawa Ikuru
Published: September 2010

Dentatorubral‐pallidoluysian atrophy is caused by polyglutamine (polyQ) expansion in atrophin‐1 (ATN1). Recent studies have shown that nuclear accumulation of ATN1 and cleaved fragments with expanded polyQ is the pathological process underlying neurodegeneration in dentatorubral‐pallidoluysian atrophy. However, the mechanism underlying the proteolytic processing of ATN1 remains unclear. In the present study, we examined the proteolytic processing of ATN1 aiming to understand the mechanisms of ATN1 accumulation with polyQ expansion. Using COS‐7 and Neuro2a cells that express the ATN1 gene, in which ATN1 was accumulated by increasing the number of polyQs, we identified a novel C‐terminal fragment containing a polyQ tract. The mutant C‐terminal fragment with expanded polyQ selectively accumulated in the cells, and this was also demonstrated in the brain tissues of patients with dentatorubral‐pallidoluysian atrophy. Immunocytochemical and biochemical studies revealed that full‐length ATN1 and C‐terminal fragments displayed individual localization. The mutant C‐terminal fragment was preferentially found in the cytoplasmic membrane/organelle and insoluble fractions. Accordingly, it is assumed that the proteolytic processing of ATN1 regulates the localization of C‐terminal fragments. Accumulation of the C‐terminal fragment was enhanced by inhibition of caspases in the cytoplasm of COS‐7 cells. Collectively, these results suggest that the C‐terminal fragment plays a principal role in the pathological accumulation of ATN1 in dentatorubral‐pallidoluysian atrophy.
Impact of Lipid Apheresis on Egr‐1, c‐Jun, c‐Fos, and Hsp70 Gene Expression in White Blood Cells
Authors: Schettler Volker , Völker Katrin , Schulz Egbert G , Wieland Eberhard
Published: September 2010

Lipid apheresis treatment has been suggested to cause oxidative stress. Cells respond to oxidative stress in many ways, including, among others, altered gene expressions. In the present investigation we investigated whether the gene expression of known stress genes was affected in the WBCs of patients undergoing lipid apheresis. For this purpose cellular early‐growth‐response gene‐1 (Egr‐1), c‐Jun, c‐Fos, and heat shock protein 70 (Hsp70) mRNA expression was followed before and immediately after lipid apheresis treatments (N = 24). Gene expression was determined by quantitative reverse transcription‐polymerase chain reaction. With the exception of c‐Fos, the expression of Egr‐1, c‐Jun, and Hsp70 mRNA was not affected in WBCs by a single lipid apheresis treatment (median [16th percentile; 84th percentile]): Egr‐1, before 0.30 (0.13; 0.53), after 0.31 (0.14; 1.33); c‐Jun, before 0.03 (0.03; 0.16), after 0.05 (0.03; 0.18); Hsp70, before 0.49 (0.23; 1.07), after 0.53 (0.20; 1.61)). Expression of c‐Fos was significantly decreased (P < 0.01) after lipid apheresis treatment (before 2.18 [1.06; 5.27], after 1.65 [0.74; 4.12]). Hsp70 and c‐Fos expression in lipid apheresis patients was not different from that in 35 healthy blood donors, whereas Egr‐1 and c‐Jun were significantly decreased (P < 0.05) in lipid apheresis patients when compared to controls (Egr‐1 0.96 [0.42; 1.83], c‐Jun 0.64 [0.40; 0.98], c‐Fos 2.77 [1.32; 4,02], Hsp70 0.43 [0.28; 0.61]). These results show that lipid apheresis procedures do not induce stress gene expression in WBCs. Therefore, all the lipid apheresis systems used seem to be safe with respect to oxidative stress and other injuries induced in WBCs due to contact with extracorporeal tubing and membranes.
Constraining the low-mass end of the initial mass function with gravitational lensing
Authors: Ferreras Ignacio , Saha Prasenjit , Leier Dominik , Courbin Frédéric , Falco Emilio E.
Published: September 2010

The low-mass end of the stellar initial mass function (IMF) is constrained by focusing on the baryon-dominated central regions of strong lensing galaxies. We study in this Letter the Einstein Cross (Q2237+0305), a z= 0.04 barred galaxy whose bulge acts as lens on a background quasar. The positions of the four quasar images constrain the surface mass density on the lens plane, whereas the surface brightness (H-band HST/NICMOS imaging) along with deep spectroscopy of the lens (VLT/FORS1) allows us to constrain the stellar mass content, for a range of IMFs. We find that a classical single power law (Salpeter IMF) predicts more stellar mass than the observed lensing estimates. This result is confirmed at the 99 per cent confidence level, and is robust to systematic effects due to the choice of population synthesis models, the presence of dust or the complex disc/bulge population mix. Our non-parametric methodology is more robust than kinematic estimates, as we do not need to make any assumptions about the dynamical state of the galaxy or its decomposition into bulge and disc. Over a range of low-mass power-law slopes (with Salpeter being Γ=+ 1.35) we find that at a 90 per cent confidence level, slopes Γ > 0 are ruled out.
Beyond the fear of discretion: Flexibility, performance, and accountability in the management of regulatory bureaucracies
Authors: Pires Roberto R. C.
Published: September 2010

This study explores the implications of different approaches to performance management for inspection work and regulatory outcomes. It assesses to what extent variations in methods for controlling discretion explain why in some cases regulatory inspectors limit themselves to the narrow boundaries of their formal mandate, while in other cases they work collaboratively with inspected firms and other organizations to develop innovative strategies that solve complex regulatory and business problems. After reviewing alternative approaches to the management of discretion, I present a natural experiment that offered an opportunity for controlled comparisons of two current attempts to reconcile bureaucratic performance with accountability: New Public Management and Experimentalist Governance. Case comparisons in the area of labor inspection in Brazil – involving severance payments, fraudulent cooperatives, and safety in construction – suggest that these two approaches to the management of regulatory bureaucracies produce considerably different inspection strategies and regulatory outcomes. The different accountability mechanisms and investigation strategies inspired by each of these approaches create different sets of incentives with direct effects on inspectors' motivation and their ability to resolve compliance problems.
Myxococcus xanthus induces actinorhodin overproduction and aerial mycelium formation by Streptomyces coelicolor
Authors: Pérez Juana , Muñoz‐Dorado José , Braña Alfredo F. , Shimkets Lawrence J. , Sevillano Laura , Santamaría Ramón I.
Published: September 2010

Interaction of the predatory myxobacterium Myxococcus xanthus with the non‐motile, antibiotic producer Streptomyces coelicolor was examined using a variety of experimental approaches. Myxococcus xanthus cells prey on S. coelicolor, forming streams of ordered cells that lyse the S. coelicolor hyphae in the contact area between the two colonies. The interaction increases actinorhodin production by S. coelicolor up to 20‐fold and triggers aerial mycelium production. Other bacteria are also able to induce these processes in S. coelicolor though to a lesser extent. These studies offer new clues about the expression of genes that remain silent or are expressed at low level in axenic cultures and open the possibility of overproducing compounds of biotechnological interest by using potent inducers synthesized by other bacteria.
Characterization of a silent sesquiterpenoid biosynthetic pathway in Streptomyces avermitilis controlling epi‐isozizaene albaflavenone biosynthesis and isolation of a new oxidized epi‐isozizaene metabolite
Authors: Takamatsu Satoshi , Lin Xin , Nara Ayako , Komatsu Mamoru , Cane David E , Ikeda Haruo
Published: September 2010

The genome‐sequenced, Gram‐positive bacterium Streptomyces avermitilis harbours an orthologue (SAV_3032) of the previously identified epi‐isozizaene synthase (SCO5222) in Streptomyces coelicolor A3(2). The sav3032 is translationally coupled with the downstream sav3031 gene encoding the cytochrome P450 CYP170A2 analogous to SCO5223 (CYP170A1) of S. coelicolor A3(2), which exhibits a similar translation coupling. Streptomyces avermitilis did not produce epi‐isozizaene or any of its oxidized derivatives, albaflavenols and albaflavenone, under in any culture conditions examined. Nonetheless, recombinant SAV_3032 protein expressed in Escherichia coli catalysed the Mg2+‐dependent cyclization of farnesyl diphosphate to epi‐isozizaene. To effect the production of epi‐isozizaene in S. avermitilis, the sav3032 gene was cloned and placed under control of a copy of the native S. avermitilis promoter rpsJp (sav4925). The derived expression construct was introduced by transformation into a large‐deletion mutant of S. avermitilis SUKA16 and the resulting transformants accumulated epi‐isozizaene. The previously characterized oxidized epi‐isozizaene metabolites (4R)‐ and (4S)‐albaflavenols and albaflavenone, as well as a previously undescribed doubly oxidized epi‐isozizaene derivative were isolated from cultures of S. avermitilis SUKA16 transformants in which sav3032 was coexpressed with the P450‐encoding sav3031. This new metabolite was identified as 4β,5β‐epoxy‐2‐epi‐zizaan‐6β‐ol which is most likely formed by oxidation of (4S)‐albaflavenol.
Taxon‐specific PCR for DNA barcoding arthropod prey in bat faeces
Authors: ZEALE MATT R. K. , BUTLIN ROGER K. , BARKER GARY L. A. , LEES DAVID C. , JONES GARETH
Published: September 2010

The application of DNA barcoding to dietary studies allows prey taxa to be identified in the absence of morphological evidence and permits a greater resolution of prey identity than is possible through direct examination of faecal material. For insectivorous bats, which typically eat a great diversity of prey and which chew and digest their prey thoroughly, DNA‐based approaches to diet analysis may provide the only means of assessing the range and diversity of prey within faeces. Here, we investigated the effectiveness of DNA barcoding in determining the diets of bat species that specialize in eating different taxa of arthropod prey. We designed and tested a novel taxon‐specific primer set and examined the performance of short barcode sequences in resolving prey species. We recovered prey DNA from all faecal samples and subsequent cloning and sequencing of PCR products, followed by a comparison of sequences to a reference database, provided species‐level identifications for 149/207 (72%) clones. We detected a phylogenetically broad range of prey while completely avoiding detection of nontarget groups. In total, 37 unique prey taxa were identified from 15 faecal samples. A comparison of DNA data with parallel morphological analyses revealed a close correlation between the two methods. However, the sensitivity and taxonomic resolution of the DNA method were far superior. The methodology developed here provides new opportunities for the study of bat diets and will be of great benefit to the conservation of these ecologically important predators.
Genetic and morphologic features for melanoma classification
Authors: Broekaert Sigrid M. C. , Roy Ritu , Okamoto Ichiro , van den Oord Joost , Bauer Jürgen , Garbe Claus , Barnhill Raymond L. , Busam Klaus J. , Cochran Alistair J. , Cook Martin G. , Elder David E. , McCarthy Stanley W. , Mihm Martin C. , Schadendorf Dirk , Scolyer Richard A. , Spatz Alan , Bastian Boris C.
Published: September 2010

Melanoma is comprised of biologically distinct subtypes. The defining clinical, histomorphologic, and molecular features are not fully established. This study sought to validate the association between genetic and histomorphologic features previously described and to determine their reproducibility and association with important clinical variables. Detailed clinical and histomorphologic features of 365 primary cutaneous melanomas were assessed by 11 pathologists and correlated with mutation status of BRAF and NRAS. There was substantial agreement in the quantitative assessment of histomorphologic features showing similar or better interobserver reproducibility than the established World Health Organization classification scheme. We confirmed that melanomas with BRAF mutations showed characteristic morphologic features (P < 0.0001) and metastasized more frequently to regional lymph nodes (P = 0.046). Importantly, melanomas without mutations were a heterogeneous group, with a subset having very similar clinical and morphological features as those with BRAF mutation raising the possibility that they are biologically related. Our study confirms an association between histomorphologic features, mutation status, and pattern of metastasis, providing criteria for a refined melanoma classification aimed at defining biologically homogeneous disease subgroups.
Humpback whales harbour a combination of specific and variable skin bacteria
Authors: Apprill Amy , Mooney T. Aran , Lyman Edward , Stimpert Alison K. , Rappé Michael S.
Published: September 2010

Investigations of marine mammal skin‐associated microbiota are limited to cultivation‐based studies of lesioned individuals, resulting in a lack of understanding about the composition of ‘normal’ skin‐associated microbial communities, their variation among individuals, and whether or not the microbial communities change with host health or environmental exposures. In this study, bacterial communities associated with the skin of 19 North Pacific humpback whales (Megaptera novaeangliae), including skin from three health‐compromised individuals, were examined using small subunit ribosomal RNA gene‐based culture‐independent techniques. These analyses revealed that the skin‐associated bacteria were significantly different from free‐living bacterial communities in the surrounding seawater. Two novel groups within the Flavobacteriaceae family of the Bacteroidetes phylum were found to be associated with multiple whales, including a species within the Tenacibaculum genus that associated with 95% of the individuals. Statistical analyses revealed that a group of eight ‘healthy’ whales harboured similar microbial communities, while the health‐compromised and other ‘healthy’ animals harboured communities that were unique to the specific animal. These results describe two components of the whale skin bacterial community: a specific and potentially co‐evolved fraction, and a more variable microbial community fraction that may offer a diagnostic‐type tool for investigating the health and life‐related events of these endangered animals.
Isolated splenic metastasis of lung adenocarcinoma
Authors: Alloubi Ihsan , Bourhaleb Zouhour , Harroudi Tijani
Published: September 2010

Splenic metastasis from lung cancer is uncommon, and isolated metastasis to the spleen is extremely rare event. Most often they are part of widespread metastatic disease and usually reported at autopsy. We report an exceedingly rare case of metastatic involvement of the spleen in an operated case of lung adenocarcinoma in a 58‐year‐old man diagnosed 12 months after resection.
Reshaping Economic Geography? Producing Spaces of Inclusive Development
Authors: Lawson Victoria
Published: September 2010

abstract

The World Development Report 2009 discusses a crucial development challenge—that of understanding spatially uneven development. The report lays out a series of policy responses to spatial unevenness that are intended to mobilize the growth‐enhancing advantages of unbalanced development while ensuring inclusive development. However, the report mobilizes a narrow view of economic development that is disconnected from place, politics, and society. In geography, which lends its name to the report, economies are theorized as embedded—as produced in and through space, rather than merely on it. Geography and spatial patterns are constitutive coproducers of political‐economic processes, not just outcomes. I elaborate how a critical geographic understanding of an “everywhere embedded economy” (Peck 2005) highlights the inseparability of economic processes from the social, political, historical, and geographic contexts which give them meaning. I connect the idea of embedded economy to a consideration of centrality of care to a humane and inclusive development. I argue that the report's emphasis on labor mobility as a key mechanism for enhancing development ignores the global division of care work that is itself built on the invisibility and undervaluation of care in mainstream versions of economic development. I conclude that “thinning borders” will not resolve questions of inequality but rather will allow those who are more powerful to exploit the resultant power differentials expressed in migration and care deficits across the globe.
Worlds Apart? Engaging with the World Development Report 2009: Reshaping Economic Geography
Authors: Peck Jamie , Sheppard Eric
Published: September 2010

abstract

Introducing a roundtable discussion of the World Bank's World Development Report 2009: Reshaping Economic Geography, this article contextualizes the report in intellectual and political terms. It reflects on the lost opportunities for, and potential limits of, engagement between the style of New Economic Geography espoused by the World Bank and the pluralist heterodoxy of economic geography “proper,” before briefly previewing the commentaries from Gillian Hart, Victoria Lawson, and Andrés Rodríguez‐Pose and the response from World Bank economists Uwe Deichmann, Indermit Gill, and Chor Ching Goh.
Economic Geographers and the Limelight: Institutions and Policy in the World Development Report 2009
Authors: Rodríguez‐Pose Andrés
Published: September 2010

abstract

The reaction of economic geographers to the World Bank's World Development Report 2009: Reshaping Economic Geography has so far been a corporatist turf‐protecting exercise. The report has been dismissed as the work of economists who completely ignore a rich tradition of work by “proper” economic geographers. However, this negative response has prevented geographers from engaging constructively with the World Bank's analysis and proposals. In this article, I argue that, while the report presents an accurate diagnosis of recent development trends and should be praised for its flexibility in providing numerous policy alternatives, geographers can significantly contribute by promoting a discussion around two key issues in the report: its treatment of institutions and its recommendation of spatially blind policies.
Quasi-invariants of complex reflection groups
Authors: Berest Yuri , Chalykh Oleg
Published: September 2010

We introduce quasi-invariant polynomials for an arbitrary finite complex reflection group W. Unlike in the Coxeter case, the space of quasi-invariants of a given multiplicity is not, in general, an algebra but a module Qk over the coordinate ring of a (singular) affine variety Xk. We extend the main results of Berest et al. [Cherednik algebras and differential operators on quasi-invariants, Duke Math. J. 118 (2003), 279–337] to this setting: in particular, we show that the variety Xk and the module Qk are Cohen–Macaulay, and the rings of differential operators on Xk and Qk are simple rings, Morita equivalent to the Weyl algebra An(ℂ) , where n=dim Xk. Our approach relies on representation theory of complex Cherednik algebras introduced by Dunkl and Opdam [Dunkl operators for complex reflection groups, Proc. London Math. Soc. (3) 86 (2003), 70–108] and is parallel to that of Berest et al. As an application, we prove the existence of shift operators for an arbitrary complex reflection group, confirming a conjecture of Dunkl and Opdam. Another result is a proof of a conjecture of Opdam, concerning certain operations (KZ twists) on the set of irreducible representations of W.
The Impact of Probabilistic Modeling in Life-Cycle Management of Nuclear Piping Systems
Authors: Pandey M. D. , Lu D. , Komljenovic D.
Published: September 2010

Flow accelerated corrosion (FAC) is a serious form of degradation in primary heat transport piping system (PHTS) of the nuclear reactor. Pipes transporting hot coolant from the reactor to steam generators are particularly vulnerable to FAC degradation, such as tight radius pipe bends with high flow velocity. FAC is a life limiting factor, as excessive degradation can result in the loss of structural integrity of the pipe. To prevent this, engineering codes and regulations have specified minimum wall thickness requirements to ensure fitness for service of the piping system. Nuclear utilities have implemented periodic wall thickness inspection programs and carried out replacement of pipes prior to reaching an unsafe state. To optimize the life-cycle management of PHTS, accurate prediction of time of replacement or “end of life” of pipe sections is important. Since FAC is a time-dependent process of uncertain nature, this paper presents two probabilistic models for predicting the end of life. This paper illustrates that the modeling assumptions have a significant impact on the predicted number of replacements and life-cycle management of the nuclear piping system. A practical case study is presented using wall thickness inspection data collected from Canadian nuclear plants.
Flow and Mass Transfer in Bends Under Flow-Accelerated Corrosion Wall Thinning Conditions
Authors: Pietralik John M. , Schefski Chris S.
Published: September 2010

The three groups of parameters that affect flow-accelerated corrosion (FAC) are the flow conditions, water chemistry, and materials. Nuclear power plant (NPP) data and laboratory tests confirm that, under alkaline water chemistry, there is a close relationship between local flow conditions and FAC rates in the piping components. The knowledge of the local flow effects can be useful for developing targeted inspection plans for piping components and predicting the location of the highest FAC rate for a given piping component. A similar evaluation applies also to the FAC in heat transfer equipments such as heat exchangers and steam generators. The objective of this paper is to examine the role of the flow and mass transfer in bends under alkaline FAC conditions. Bends experience increased FAC rates compared with straight pipes, and are the most common components in piping systems. This study presents numerical simulations of the mass transfer of ferrous ions and experimental results of the FAC rate in bends. It also shows correlations for mass transfer coefficients in bends and reviews the most important flow parameters affecting the mass transfer coefficient. The role of bend geometry and, in particular, the short and long radii, surface roughness, wall shear stress, and local turbulence, is discussed. Computational fluid dynamics calculations and plant artifact measurements for short- and long-radius bends are presented. The effect of the close proximity of the two bends on the FAC rate is also examined based on CANDU (CANDU is a registered trademark of the Atomic Energy of Canada Limited) NPP inspection data and compared with literature data.
Semi-Active Sloshing Suppression Control of Liquid in Vessel With Bulkhead
Authors: Kobayashi Nobuyuki , Koyama Yusuke
Published: September 2010

A semi-active sloshing suppression control method for the contained liquid in the closed vessel is presented. The presented method uses the air spring effect of the gas chamber on the liquid surface, when the closed vessel is divided into two separated compartments with the vertical bulkhead in it so as to allow communication between two compartments at the lower part of the vessel. When the valve that is laid on the bulkhead between the two gas chambers closes, the spring effect of the gas chamber arises. On the contrary, when the valve opens, the spring effect of the gas chamber diminishes. A switching control algorithm of the valve operation is designed to decrease the sloshing response. The effectiveness of the presented semi-active sloshing suppression control method is examined with numerical simulations and the scaled model experiment. As the result, the presented method is verified to be effective to suppress the sloshing while the consuming energy to control the valve is small.
The Effect of Fins on Fluidelastic Instability in In-Line and Rotated Square Tube Arrays
Authors: Lumsden Robert H. , Weaver David S.
Published: September 2010

An experimental program was conducted to examine fluidelastic instability in in-line and rotated square finned tube arrays. Three arrays of each geometry type were studied: two with serrated, helically wound finned tubes of different fin densities and the third is a bare tube, which had the same base diameter as the finned tubes. The finned tubes under consideration were commercial finned tubes of a type typically used in the fossil and process industries. The addition of fins to tubes in heat exchangers enhances heat transfer due to the increased surface area and the turbulence produced by the flow moving over the fins. The resulting flow pattern/distribution due to the fins is, therefore, more complex than in bare tube arrays. Previous research has shown that an effective diameter of a finned tube is useful in the prediction of vortex shedding. This concept is used to compare the finned tube results with the existing bare tube array guidelines for fluidelastic instability. All of the tube arrays in the present study have the same tube pitch and have been scaled to have the same mass ratio. The results for rotated square arrays suggest that the use of an effective diameter is beneficial in the scaling of fluidelastic instability and the finned tube results are found to fit within the scatter of the existing data for fluidelastic instability. For in-line square arrays, the results indicate that fins significantly increase the stability threshold. An earlier version of this paper appeared at the ASME 2007 PVP Division Conference, PVP2007-26597.
Heat Transfer and Stress Analysis of Coke Drum for a Complete Operating Cycle
Authors: Xia Zihui , Ju Feng , Du Plessis Pierre
Published: September 2010

Coke drums experience severe thermal and mechanical loadings during operation, and the reliability and safety of the coke drums are critical to the industry. The objective of this study is to analyze temperature and stress of the coke drum for a complete process cycle. The thermal analysis model of the coke drum is first developed incorporating appropriate boundary conditions. The heat transfer coefficients at the inner surface of the coke drum, which change with the operation stages and the levels of oil filling and water quenching, are determined based on the temperature measurement data at a certain location on the outer surface of the coke drum. The temperature history of the coke drum of a complete cycle is then obtained by finite element heat transfer analysis, and computed temperature data are used for the stress analysis of the coke drum, including both thermal and mechanical loadings. It is found from numerical results that the clad experiences a biaxial stress cycling with maximum value higher than the yield limit of the material, which coincide with the low cycle fatigue failure of the structure.
High-Density Polyethylene Piping Butt-Fusion Joint Examination Using Ultrasonic Phased Array
Authors: Frederick Caleb , Porter Allen , Zimmerman David
Published: September 2010

With the increasing use of high-density polyethylene (HDPE) piping for nuclear applications, nondestructive evaluation is an important tool for evaluation of the integrity in fused joints. This paper will discuss the method of using ultrasonic phased array for inspecting butt-fusion (BF) joints in HDPE piping. The benefit of phased array is the ability to perform a volumetric inspection using multiple angles, which greatly increases the probability of detection of defects and allows the data to be analyzed using a representative two-dimensional image of the joint. It has been determined that successfully producing BF joints is highly dependent on environmental and mating-surface conditions. The primary defects of concern are lack-of-fusion, an area of the joint where there is no bond, cold fusion, an area of partial bond, and inclusion. Phased array has successfully demonstrated the ability of detecting and characterizing these defects using low frequency ultrasound. Factors addressed include joint location, wall thickness, material temperature, transducer wedge material, and manual versus automated data acquisition.
A Probabilistic Lifetime Prediction Technique for Piping Under Creep Conditions
Authors: Delph T. J. , Berger D. L. , Harlow D. G. , Ozturk M.
Published: September 2010

We outline here a simple approximate method of lifetime prediction for high-temperature, internally pressurized piping components that takes into account the very large scatter present in the creep data for commonly used piping materials. This scatter is so large as to make deterministic methods of life prediction quite problematic. The method presented here is based upon the well-known Monte Carlo technique, and makes use of the standard damage fraction as the basic measure of creep damage. The method yields predictions of the probability of failure after a fixed operating time, assumed to be large.
A Reliability-Based Approach for Low-Cycle Fatigue Design of Class 2 and 3 Nuclear Piping
Authors: Avrithi Kleio , Ayyub Bilal M.
Published: September 2010

This paper presents a reliability-based low-cycle fatigue design approach for class 2 and 3 nuclear pipes. Initially, the methodology and background for the design of the pipes according to the ASME Boiler and Pressure Vessel (B&PV) Code is presented. Then a probabilistic design methodology based on the ASME B&PV Code and focused on straight pipes with butt-welds is presented. The method ensures an acceptable reliability level for piping by keeping the failure probability within some upper threshold and accounting for the uncertainties of the design variables. In opposition, the current design may result in diverse and often unknown probabilities of failure for piping. A computational example illustrates the developed method.
Plastic Collapse Assessment of Thick Vessels Under Internal Pressure According to Various Hardening Rules
Authors: Chaaba A.
Published: September 2010

This paper aims to deal with plastic collapse assessment for thick vessels under internal pressure, thick tubes in plane strain conditions, and thick spheres, taking into consideration various strain hardening effects and large deformation aspect. In the framework of von Mises’ criterion, strain hardening manifestation is described by various rules such as isotropic and/or kinematic laws. To predict plastic collapse, sequential limit analysis, which is based on the upper bound formulation, is used. The sequential limit analysis consists in solving sequentially the problem of the plastic collapse, step by step. In the first sequence, the plastic collapse of the vessel corresponds to the classical limit state of the rigid perfectly plastic behavior. At the end of each sequence, the yield stress and/or back-stresses are updated with or without geometry updating via displacement velocity and strain rates. The updating of all these quantities (geometry and strain hardening variables) is adopted to conduct the next sequence. As a result of this proposal, we get the limit pressure evolution, which could cause the plastic collapse of the device for different levels of hardening and also hardening variables such as back-stresses with respect to the geometry change.
Calculating Thermal Gradients in a B31.1 Welding End Transition Joint by Formulae
Authors: Creates David H.
Published: September 2010

Fatigue evaluation in B31.1 is currently done based on equations 1 and 2 of ASME B31.1-2007 Power Piping, which only considers the displacement load ranges. However, fatigue damage, in addition to displacement load ranges, is occurring in B31.1 piping due to pressure cycling and thermal gradients. To exacerbate this, power plant design pressures and temperatures are rising, new materials are being introduced, pipes and attached components are becoming increasingly thick, and owners are requiring power plants to heat-up and cool-down at faster rates. Also, power plant owners are more and more interested in extending the life of power plants beyond their original design life. This article takes the first step in addressing the pressing need to address this additional fatigue damage by quantifying thermal gradients in the prevalent B31.1 welding end transitions in Fig. 127.4.2, or tapered transition joints (TTJs) in Appendix D, of ASME B31.1-2007 Power Piping by formulae to be able to evaluate their contribution to fatigue (see PVP2009-77148 [A Procedure to Evaluate a B31.1 Welding End Transition Joint to Include the Fatigue Effects of Thermal Gradients for Design and Plant Life Extension]). The disadvantage of this approach is that the conservatisms inherent in the calculations of thermal gradients, as per ASME Section III Subsection NB3600-2007, are also inherent in these calculations and may produce unacceptable results when evaluated as per PVP2009-77148 [A Procedure to Evaluate a B31.1 Welding End Transition Joint to Include the Fatigue Effects of Thermal Gradients for Design and Plant Life Extension]. If the results are unacceptable, it is a warning that something else needs to be done. The advantage of this approach is that it eliminates the need for a computer program to quantify these thermal gradients, a computer program that is not normally accessible to the B31.1 designer anyway. Instead, the formulae use the data that are available to the B31.1 designer, namely, physical geometry, thermal conductivity, and rate of temperature change in the fluid in the pipe. This will further help to preserve the integrity of the piping pressure boundary and, consequently, the safety of personnel in today’s power plants and into the future.
Stress Intensity Factors for Partially Autofrettaged Pressurized Thick-Walled Cylinders Containing Closely and Densely Packed Cracks
Authors: Ma Q. , Levy C. , Perl M.
Published: September 2010

Due to acute temperature gradients and repetitive high-pressure impulses, extremely dense internal surface cracks can be practically developed in highly pressurized thick-walled vessels, typically in gun barrels. In the authors’ previous studies, networks of typical radial and longitudinal-coplanar, semi-elliptical, internal surface cracks have been investigated assuming both ideal and realistic full autofrettage residual stress fields (ε=100%). The aim of the present work is to extend the analysis twofold: to include various levels of partially autofrettaged cylinders and to consider configurations of closely and densely packed radial crack arrays. To accurately assess the stress intensity factors (SIFs), significant computational efforts and strategies are necessary, especially for networks with closely and densely packed cracks. This study focuses on the determination of the distributions along the crack fronts of KIP, the stress intensity factor due to internal pressure KIA, the negative stress intensity factor resulting from the residual stress field due to ideal or realistic autofrettage, and KIN, the combined SIF KIN=KIP−|KIA|. The analysis is performed for over 1000 configurations of closely and densely packed semicircular and semi-elliptical networked cracks affected by pressure and partial-to-full autofrettage levels of ε=30–100%, which is of practical benefit in autofrettaged thick-walled pressure vessels. The 3-D analysis is performed via the finite element method and the submodeling technique employing singular elements along the crack front and the various symmetries of the problem. The network cracks will include up to 128 equally spaced cracks in the radial direction: with relative longitudinal crack spacing, 2c/d, from 0.1 to 0.99; autofrettage level of 30–100%; crack depth to wall thickness ratios, a/t, from 0.01 to 0.4; and, cracks with various ellipticities of crack depth to semicrack length, a/c, from 0.2 to 2. The results clearly indicate that the combined SIFs are considerably influenced by the three dimensionality of the problem and the Bauschinger effect (BE). The Bauschinger effect is found to have a dramatic effect on the prevailing combined stress intensity factors, resulting in a considerable reduction of the fatigue life of the pressure vessel. While the fatigue life can be finite for ideal autofrettage, it is normally finite for realistic autofrettage for the same crack network. Furthermore, it has been found that there are differences in the character of the SIFs between closely packed and densely packed crack networks, namely, more dramatic drop-offs in KIA and KIN at the crack-inner bore interface for densely packed cracks further influenced by crack depth.
Application of Microfocus Rod Anode in Qualification of Tube-to-Tube-Sheet Welds in Steam Generators
Authors: Vaidya P. R. , Narain D. , Kumar Sunil
Published: September 2010

Tube-to-tube-sheet (TTS) welds, occurring in heat exchangers, condensers, and steam generators, are exempted from volumetric nondestructive examination, such as radiography or ultrasonic tests, due to their geometry. An approach of stricter quality control at qualification stage is adopted, apart from tests like liquid penetrant test and leak test applied to production welds. For qualification purpose, a mock up block is destructively examined for weld quality by microscopy and/or macroscopic examination. This paper shows that it is possible to carry out radiography of TTS welds using microfocal x-ray unit with back-throw type rod anode attachment, which sends radiation in nearly radial direction. It demonstrates the use of the same technique for the qualification weld block also. It further shows that the qualification weld slices can be radiographed in axial direction to enable 100% volumetric examination. Besides, it will make metallography more effective and meaningful; instead of a random section, it can then address the plane with a flaw using the help from radiography test. The paper suggests that the code adopt radiography in addition to metallography during qualification for better quality assurance.
Modified Formulation of Layer Stresses Due to Internal Pressure of a Layered Vessel With Interlayer Gaps
Authors: Xu Shugen , Wang Weiqiang , Song Mingda , Li Mengli , Tang Jun
Published: September 2010

In this paper, the modified formulae have been provided. They can be used to calculate the stress in layers with gaps of a layered cylinder. In order to obtain the modified formulae, a detailed derivation process has also been presented in this paper. Meanwhile, we have clarified the derivation process and application range of Pimshtein’s formulae and corrected the errors. We have also indicated the shortcomings of the formulae given by Huang, Chen and Lai, and the ASME code. Finally, a practical example is presented to show how the modified formulae are applied. Calculation results obtained from the modified formulae have been compared with those obtained by finite element method and above mentioned formulae; it shows that the results from the modified formulae are in accordance with finite element results.
Failure Pressure in Corroded Pipelines Based on Equivalent Solutions for Undamaged Pipe
Authors: Bony M. , Alamilla J. L. , Vai R. , Flores E.
Published: September 2010

Simple and accurate approaches to predict failure pressures in corroded pipelines are outlined in this work. It is shown that failure pressures for corroded pipelines can be predicted from the solution for undamaged pipelines using an equivalent wall thickness. Three different yield criteria (Tresca, ASSY (average shear stress yield), and von Mises) are reviewed in the light of reported experimental burst pressures. At first, failure pressures for cylindrical vessels with an infinitely long groove are studied by means of numerical simulations. The effect of groove size (depth and width) over the pipeline performance is quantified through a model. Finally, the scheme is extended to estimate the failure pressure of thin walled vessels with irregular finite defects.