bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing the accuracy of density‐independent demographic models for predicting species ranges
Authors: Holden Matthew H. , Yen Jian D. L. , Briscoe Natalie J. , Lahoz‐Monfort José J. , Salguero‐Gómez Roberto , Vesk Peter A. , Guillera‐Arroita Gurutzeta
Published: December 2020

Accurately predicting species ranges is a primary goal of ecology. Demographic distribution models (DDMs), which correlate underlying vital rates (e.g. survival and reproduction) with environmental conditions, can potentially predict species ranges through time and space. However, tests of DDM accuracy across wide ranges of species' life histories are surprisingly lacking. Using simulations of 1.5 million hypothetical species' range dynamics, we evaluated when DDMs accurately predicted future ranges, to provide clear guidelines for the use of this emerging approach. We limited our study to deterministic demographic models ignoring density dependence, since these models are the most commonly used in the literature. We found that density‐independent DDMs overpredicted extinction if populations were near carrying capacity in the locations where demographic data were available. However, DDMs accurately predicted species ranges if demographic data were limited to sites with mean initial abundance less than one half of carrying capacity. Additionally, the DDMs required demographic data from at least 25 sites, over a short time‐interval (< 10 time‐steps), as populations initially below carrying capacity can saturate in long‐term studies. For species with demographic data from many low density sites, DDMs predicted occurrence more accurately than correlative species distribution models (SDMs) in locations where the species eventually persisted, but not where the species went extinct. These results were insensitive to differences in simulated dispersal, levels of environmental stochasticity, the effects of the environmental variables and the functional forms of density dependence. Our findings suggest that deterministic, density‐independent DDMs are appropriate for applications where locating all possible sites the species might occur in is prioritized over reducing false presence predictions in absent sites. This makes DDMs a promising tool for mapping invasion risk. However, demographic data are often collected at sites where a species is abundant. Density‐independent DDMs are inappropriate in this case.
The prevalence of traumatic dental injuries in primary teeth: A systematic review and meta‐analysis
Authors: Patnana Arun Kumar , Chugh Ankita , Chugh Vinay Kumar , Kumar Pravin , Vanga Narasimha Rao V. , Singh Surjit
Published: December 2020

Background/Aims

The varied prevalence of traumatic dental injuries (TDI) in primary teeth around the globe raises a serious knowledge gap in the available literature. The aim of this study was to evaluate the prevalence of TDI in primary teeth and also to evaluate the different factors associated with TDI in primary teeth.

Materials and Methods

Comprehensive searches were performed in PubMed, Embase, Google Scholar, and The Cochrane Central Register of Controlled Trials with predefined search criteria. The primary outcome was the prevalence of TDI in primary teeth, and the secondary outcomes were the factors associated with TDI in primary teeth. Qualitative analysis was done using the Newcastle‐Ottawa scale adapted for cross‐sectional studies. The random‐effect model was used for meta‐analysis, and meta‐regression analysis was done to evaluate the heterogeneity between the included studies. Meta‐analysis was done using the “meta” package of “R” language. The overall quality of evidence was assessed using GRADEpro GDT software.

Results

A total of 24 cross‐sectional studies met the inclusion criteria representing 4876 TDIs in 22 839 children aged between 0 and 6 years old. The overall prevalence of TDI in primary teeth was 24.2% (95% CI: 18.24‐31.43, P = 0, I2 = 99%). Falls contributed the highest number of TDI ‐ 59.3% (95% CI: 41.05‐76.40, P < .01, I2 = 98%) ‐ in primary teeth. The most common type of tooth fracture in primary teeth was an enamel fracture (61.9%), and prevalence of TDI in children with incompetent lip closure was 49.4%.

Conclusion

The prevalence of TDI in cross‐sectional studies of primary teeth was 24.2% with very low quality of evidence. Falls contributed the highest number of TDI in primary teeth, accounting for 59.3%. Children with incompetent lip closure have the highest prevalence (49.4%) of TDI in primary teeth.
A guide to the design of synthetic gene networks in mammalian cells
Authors: Verbič Anže , Praznik Arne , Jerala Roman
Published: December 2020

Synthetic biology aims to harness natural and synthetic biological parts and engineering them in new combinations and systems, producing novel therapies, diagnostics, bioproduction systems, and providing information on the mechanism of function of biological systems. Engineering cell function requires the rewiring or de novo construction of cell information processing networks. Using natural and synthetic signal processing elements, researchers have demonstrated a wide array of signal sensing, processing and propagation modules, using transcription, translation, or post‐translational modification to program new function. The toolbox for synthetic network design is ever‐advancing and has still ample room to grow. Here, we review the diversity of synthetic gene networks, types of building modules, techniques of regulation, and their applications.
Species sensitivities to a global pollutant: A meta‐analysis on acoustic signals in response to anthropogenic noise
Authors: Kunc Hansjoerg P. , Schmidt Rouven
Published: December 2020

Anthropogenically driven environmental changes affect our planet at an unprecedented rate. Among these changes are those in the acoustic environment caused by anthropogenic noise, which can affect both animals and humans. In many species, acoustic communication plays a crucial role to maintain social relationships by exchanging information via acoustic signals. However, how species relying on acoustic communication differ in their adjustments to anthropogenic noise is little understood. Yet, this is crucial because protecting species effectively depends on our capability to predict how species differ in their response to human‐induced environmental changes. Using a phylogenetically controlled meta‐analysis, we quantified differences in adjustments of acoustic signals to anthropogenic noise among species. The effect sizes included in the analysis were obtained from noise exposure experiments, as only carefully controlled experiments allow to establish cause‐and‐effect relationships. We found that animals changed acoustic signals when exposed to noise, but the magnitude and the direction of adjustments differed among species. Given the importance of communication in the animal kingdom, these adjustments can affect social relationships in many species. The diversity of responses among species highlights the necessity to assess the effect of environmental stressors not only for a few species, because an effect may be positive in one species but negative in another depending on the species’ biology. Thus, an effective conservation approach to protect different species is to preserve natural soundscapes of ecosystems to which species have adapted to by reducing or mitigating the emission of anthropogenic noise into the environment.
Inter‐ and intraspecific selection in alien plants: How population growth, functional traits and climate responses change with residence time
Authors: Brendel Marco R. , Schurr Frank M. , Sheppard Christine S.
Published: December 2020

Aim

When alien species are introduced to new ranges, climate or trait mismatches may initially constrain their population growth. However, inter‐ and intraspecific selection in the new environment should cause population growth rates to increase with residence time. Using a species‐for‐time approach, we test whether with increasing residence time (a) negative effects of climatic mismatches between the species’ new and native range on population growth weaken, and (b) functional traits converge towards values that maximize population growth in the new range.

Location

Germany.

Time period

12,000 years BP to present.

Major taxa studied

Forty‐six plant species of the Asteraceae family.

Methods

We set up a common‐garden mesocosm‐experiment using annual plant species with a wide range of residence times (7–12,000 years) and followed their population dynamics over 2 years. We calculated climatic distance between the common garden and the species’ native range. We also measured key functional traits of each species to analyse trait–demography relationships and test trait convergence with increasing residence time.

Results

We found no support for the hypothesis that negative effects of climatic mismatches on population growth weaken with residence time. However, seed mass had a clear negative effect on population growth. As expected under such strong directional selection between or within species, increasing residence time led seed mass to converge to low values that increase population growth. Accordingly, population growth tended to increase with residence time.

Main conclusions

We identify trait but not climatic mismatches as important constraints on population growth of invaders. Understanding how inter‐ and intraspecific selection shapes functional traits of alien species should improve the predictability of future invasions and help understanding of limits to the population growth and spread of invaders already present. In a broader context, this study contributes to the conceptual integration of invasion biology with community, functional and population ecology.
Prevalence of malignant neoplastic oral lesions among children and adolescents: A systematic review and meta‐analysis
Authors: de Paula Dayrine Silveira , Nóbrega Malta Cássia Emanuella , de Brito Wendy Honório , Mota Lemos José Vitor , Cetira Fillho Edson Luiz , Gurgel Costa Fábio Wildson , Nunes Alves Ana Paula Negreiros , de Barros Silva Paulo Goberlânio
Published: December 2020

Background

Malignant neoplasms that affect children and adolescents are predominantly embryonic and generally affect blood system cells and supporting tissues.

Aim

This study aimed to summarize the scientific evidence about the prevalence of malignant lesions in the oral cavity of children and adolescents.

Design

In this systematic review and meta‐analysis (PROSPERO CRD42020158338), data were obtained from seven databases and the gray literature. Cross‐sectional observational studies on the prevalence of biopsied oral pediatric malignancies were included. The Newcastle‐Ottawa Scale assessed the quality of the included studies, and the GRADE approach evaluated the evidence certainty. The meta‐analysis prevalence was calculated using MedCalc® software, adopting a 95% confidence level (CI; random‐effect model).

Results

Forty‐two studies were included in the meta‐analysis. Of the 64,522 biopsies, the prevalence of malignant lesions was 1.93% (n = 1,100; 95% CI = 1.21%‐2.80%). Countries with a low socioeconomic profile showed the highest prevalence. The sample size did not influence the prevalence of oral malignancies, and unspecified lymphomas (12.08%; 95% CI = 5.73%‐20.37%) and rhabdomyosarcoma (10.53%; 95% CI = 7.28%‐14.30%) were the most common lesions.

Conclusions

Oral malignant lesions biopsied in children and adolescents had a prevalence of <3%, and lymphomas and sarcomas were the most prevalent lesions.
The staging and grading system in defining periodontitis cases: consistency and accuracy amongst periodontal experts, general dentists and undergraduate students
Authors: Marini Lorenzo , Tonetti Maurizio S. , Nibali Luigi , Rojas Mariana A. , Aimetti Mario , Cairo Francesco , Cavalcanti Raffaele , Crea Alessandro , Ferrarotti Francesco , Graziani Filippo , Landi Luca , Sforza Nicola M. , Tomasi Cristiano , Pilloni Andrea
Published: December 2020

Aim

The objective of this study was to evaluate consistency and accuracy of the periodontitis staging and grading classification system.

Methods

Thirty participants (10 periodontal experts, 10 general dentists and 10 undergraduate students) and a gold‐standard examiner were asked to classify 25 fully documented periodontitis cases twice. Fleiss kappa was used to estimate consistency across examiners. Intraclass correlation coefficient (ICC) was used to calculate consistency across time. Quadratic weighted kappa and percentage of complete agreement versus gold standard were computed to assess accuracy.

Results

Fleiss kappa for stage, extent and grade were 0.48, 0.37 and 0.45 respectively. The highest ICC was provided by students for stage (0.91), whereas the lowest ICC by general dentists for extent (0.79). Pairwise comparisons against gold standard showed mean value of kappa >0.81 for stage and >0.41 for grade and extent. Agreement with the gold standard for all three components of the case definition was achieved in 47.2% of cases. The study identified specific factors associated with lower consistency and accuracy.

Conclusions

Diagnosis was highly consistent across time and moderately between examiners. Accuracy was almost perfect for stage and moderate for grade and extent. Additional efforts are required to improve training of general dentists.
Innovation in flood risk management: An ‘Avenues of Innovation’ analysis
Authors: Guerriero Rebecca , Penning‐Rowsell Edmund C.
Published: December 2020

Innovation in flood risk management (FRM) is a driver for change. Research, however, is sparse in this area, and innovation itself appears to be left largely to chance. This paper uses a ’systems of innovation’ approach, defining ’avenues’ of innovation, to explore factors that promote or inhibit innovation. The research is based on in‐depth interviews with 10 leading figures in FRM in the United Kingdom, and describes the interactions and iterations involved. We conclude that in terms of practice the encouragement of champions should be enhanced, risk cultures require concerted attention to minimise risk aversion, learning should be facilitated, and innovation scaled up to maximise its effectiveness. We aim also to add to the literature on innovation systems, providing a case study of a complex field previously unexplored in this regard. Detailed innovation‐encouraging processes here need to be better understood and FRM policies and practices adjusted accordingly.
Effect of lactic acid stress on biofilm formation of Escherichia coli O26 at different temperatures
Authors: Mi Xiaoyu , Hu Jie , Zhang Su , Wang Siqi , Zhao Wangchen , Wang Longfeng , Jiang Yun
Published: December 2020

Similar to Escherichia coli O157, non‐O157 also inherits certain acid resistance, and its stress response can be induced under acidic conditions, which may be affected by temperature. In this study, O26, the main serotype of non‐O157 E. coli, was investigated in order to evaluate the effect of lactic acid stress on its biofilm formation (BF) at different temperatures. Firstly, the BF ability of 22 isolates of E. coli O26 were compared by means of crystal violet staining and the result showed that all strains had certain BF ability with variation among strains. Then, the strain 126Z with strong capacity and strain G13Z2 with medium capacity were selected for BF experiment in acidic TSB (pH 4.0 and 5.0, adjusted with lactic acid) at 15°C and 25°C, respectively. The results showed that the BF of O26 was decreased with increasing concentration of lactic acid, and the higher the concentration of lactic acid was, the less the amount of biofilm formed. Moreover, the effect of temperature on BF of different capacity strains was related to the pH value, that is, with a lower concentration of lactic acid, the higher the temperature was, the faster the biofilm amount increased. Under a higher acid concentration, the BF of two strains showed different dynamic changes and were inhibited in the later stage, in which the biofilm amount of 126Z decreased significantly at 15°C, while that of G13Z2 decreased more significant at 25°C. This observation was further confirmed by scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM). This finding suggests that combined temperature and lactic acid intervention may be an effective method to prevent BF, and the results of present work would provide scientific basis for the risk assessment of E. coli O26 in food processing.
Applying free word association to understand the perception of fish as a meal by Brazilians with different consumption frequencies
Authors: Viana Fernanda M. , Deliza Rosires , Monteiro Maria Lúcia G. , Martins Inayara B. A. , de Oliveira Denize C. R. , Conte‐Junior Carlos A.
Published: December 2020

The aim of the present study was to investigate through free word association the Brazilian consumers' perception of fish as a meal and to explore whether different fish consumption frequencies play a role. The participants were split into high, occasional, and low consumption groups according to their self‐reported fish consumption frequency. Brazilian consumers' general associations with fish were strongly related to health benefits, which was considered a motivating factor for the high consumption group. However, for the low consumption group, the unfamiliarity, the low convenience and the high price represent barriers to fish consumption. Although they did not present negative feelings regarding fish, it was not possible to determine the factors that influence fish consumption for the group of occasional consumers. The elaboration of semi ready‐to‐eat products from fish residues and further studies focusing on occasional consumers can be strategies to increase the Brazilian per capita consumption of fish.

Practical Applications

Fish is an important source of high quality nutrients and its intake contributes to maintaining a healthy diet. However, the per capita consumption of this matrix is still low in Brazil. The present study observed that the perception of Brazilian consumers regarding fish as a meal was significantly affected by their fish consumption frequency. Therefore, the different consumer profiles must be taken into account for the development of more appropriate marketing and communication strategies aimed at increasing the consumption of this important product in the country.
Exploration of the Effects of Rural Obstetric Unit Closures on Birth Outcomes in North Carolina
Authors: Sullivan Margaret H. , Denslow Sheri , Lorenz Kathleen , Dixon Suzanne , Kelly Emma , Foley Kathleen A.
Published: December 2020

Purpose

Closures of rural labor and delivery (L/D) units have prompted national and state‐based efforts to assess the impact on birth outcomes. This study explores local effects of L/D closures in rural areas of North Carolina (NC).

Methods

This is a retrospective cohort study of birth outcomes of 4,065 women in 5 rural areas of NC with L/D unit closures between 2013 and 2017. Outcomes were abstracted from birth certificate data from the NC Vital Statistics Reporting System. Localized outcomes 1 year prior to L/D unit closure were compared with outcomes 1 and 2 years post closure, including: (1) birth location and demographics, (2) change in travel patterns for birth, and (3) birth outcomes, including rates of labor induction, cesarean deliveries, maternal morbidity, and neonatal outcomes.

Findings

Before closures, 25%‐56% of deliveries occurred outside county of residence. Commercially insured and college‐educated women were more likely to deliver out‐of‐area. Closures increased travel distance to delivery hospital an average of 7‐27 miles. In 2 areas, cesarean delivery rates decreased despite an increase in labor inductions. There was also variability between areas in prenatal care adequacy and breastfeeding.

Conclusions

We found that L/D unit closures in rural NC disproportionately affected women on Medicaid. The impact showed area‐specific variability, highlighting effects potentially masked by statewide or national analyses. Implications for future L/D closures would be eased by regional coordination and planning to mitigate negative effects, and state and national policies should address the excess burden placed on vulnerable populations.
Sleep−wake cycle dysregulation in idiopathic REM sleep behaviour disorder
Authors: Liguori Claudio , Zuccarelli Vittorio , Spanetta Matteo , Izzi Francesca , Biagio Mercuri Nicola , Placidi Fabio
Published: December 2020

Alteration of the circadian sleep−wake rhythm has been suggested in patients affected by idiopathic rapid eye movement sleep behaviour disorder. Because actigraphy is the validated instrument to monitor the sleep−wake cycle, the aim of the present study was to investigate the circadian sleep−wake rhythm in patients with idiopathic rapid eye movement sleep behaviour disorder compared with healthy aged controls. Fourteen‐day actigraphic recording, a comprehensive sleep interview, and cognitive and behavioural domains were investigated in patients affected by idiopathic rapid eye movement sleep behaviour disorder, and compared with controls similar for age, sex and cognitive performances. Patients with idiopathic rapid eye movement sleep behaviour disorder showed reduced relative amplitude and alteration of both sleep and wake compared with controls. Patients with idiopathic rapid eye movement sleep behaviour disorder also showed subjective sleep and wake complaints, and higher scores at the Beck Depression Inventory, compared with controls. Beck Depression Inventory scores correlated with sleep actigraphic parameters, such as sleep latency, sleep efficiency, time in bed, and relative amplitude. Therefore, the present study showed the dysregulation of the sleep−wake cycle in patients with idiopathic rapid eye movement behaviour disorder. Moreover, depressive symptoms documented in patients with idiopathic rapid eye movement sleep behaviour disorder correlated with the sleep−wake rhythm dysregulation.
“I got tested at home, the help came to me”: acceptability and feasibility of home‐based TB testing of household contacts using portable molecular diagnostics in South Africa
Authors: Medina‐Marino Andrew , de Vos Lindsey , Bezuidenhout Dana , Denkinger Claudia M. , Schumacher Samuel G. , Shin Sanghyuk S. , Stevens Wendy , Theron Grant , van der Walt Martie , Daniels Joseph
Published: December 2020

Objective

The effectiveness of household contact investigations is limited by low referral uptake for clinic‐based TB testing by symptomatic household contacts. We qualitatively investigated the acceptability and perceived benefits of home‐based TB testing using a portable GeneXpert‐I instrument (GX‐I) in an urban South African township.

Methods

In‐depth interviews were conducted with household contacts tested and those that observed testing. Semi‐structured interviews explored household contact’s understanding of TB, perceptions of the GX‐I device and testing procedures, confidentiality, willingness to refer others, and views on home‐ vs. clinic‐based testing. Focus group discussions with home‐based TB testing implementing staff assessed operational considerations for scale‐up. Data were analysed using a constant comparison approach to qualitatively evaluate the acceptability and feasibility of home‐based TB testing.

Results

Thirty in‐depth interviews and two focus group discussions were conducted. Observing one’s own sputum being tested resulted in an emergent trust in home‐based TB testing, the GX‐I device and one’s test results. Home‐based TB testing was considered convenient, helped to overcome apathy towards testing and mitigated barriers to clinic‐based testing. Perceptions that home‐based TB testing contributes to improved household and community health resulted in an emergent theme of alleviation of health insecurities. Operational concerns regarding inadvertent disclosure of one’s diagnosis to household members and time spent in people’s homes were identified.

Conclusions

Home‐based TB testing was acceptable and feasible. Individuals expressed belief in the machine by being able to witness the testing process. Though most themes mirrored qualitative studies of home‐based HIV testing, the alleviation of health insecurities theme is unique to home‐based TB testing. Future research must evaluate the impact of home‐based TB testing on case finding yield, time‐to‐treatment initiation and household outcomes.
Numerical Investigation of a Partially Loaded Supersonic Organic Rankine Cycle Turbine Stage
Authors: Ziaja Karl , Post Pascal , Sembritzky Marwick , Schramm Andreas , Willers Ole , Kunte Harald , Seume Joerg R. , di Mare Francesca
Published: December 2020

The organic Rankine cycle (ORC) represents an emerging technology aimed at exploiting lower temperature heat sources, such as waste heat in industrial processes or exhaust heat in combustion engines. One key aspect of this technology is the efficient and economical operation at part load, typically realized by a partial admission control, which is challenging to predict numerically. Full-annulus computation can only be avoided applying empirical partial admission loss models to conventional full-admission computations. This article aims at assessing the reliability of such a loss model under real-gas and supersonic conditions as a first step toward knowledge-based improved loss models. Three different operating points of an 18.3 kW ORC turbine working with an ethanol–water mixture with two open stator passages (2 × 36 deg) are considered. Full-annulus computational fluid dynamics (CFD) computations are compared to experimental data and results of simulations in a conventional, full-admission, periodic 72 deg-sector model with application of a one-dimensional partial admission loss model. The experimentally obtained mass flow rate and efficiency are matched overall within their measurements accuracy. By highest inlet total pressure, the computed efficiency deviates about 4% from the experiments. Predictions of efficiency based on the full-admission and loss model correction deviate from full-annulus computations less than 1%. These findings suggest that the used empirical correlations for partial admission losses can provide acceptable results in the configuration under investigation.
Grade and Temperature Dependent Reference Curves for Realistic Fen Quantification of Austenitic Stainless Steels
Authors: Seppänen Tommi , Alhainen Jouni , Arilahti Esko , Solin Jussi
Published: December 2020

Environmental effects of LWR coolant need to be factored in when defining cumulative fatigue usage of primary circuit components. The basis is a set of codified design rules and fatigue design curves, based on experimental data.

To accurately quantify environmental effects, the reference curve in air to which fatigue life in water is compared shall be as reliable as possible. Literature studies and accumulated data at VTT reveal that the use of common reference curves for a wide range of austenitic stainless steel alloys and temperatures is unreliable. Some design codes already include measures to consider this but ASME III is not yet among them. The ASME III design curve is adopted from NUREG/CR-6909 and contains no consideration for dependence of temperature or stainless steel grade.

Two different stainless steel grades, AISI 304L and 347, have previously been used in environmentally-assisted fatigue experiments at VTT. In this paper, reference curves for the AISI 304L heat are presented at room temperature and 325 °C to complement the curves already available for AISI 347. Demonstration of realistic environmental effect quantification is done using these reference curves as an alternative to the NUREG methodology.
Analysis of the Flange Seal Groove Cracking in a Hydrocracking Reactor
Authors: Zhuang Fakun , Liu Wen , Xie Guoshan , Shao Shanshan , Han Zhiyuan
Published: December 2020

The hydrocracking reactor, serving at the high temperature and pressure and containing S and N elements in medium, are the key equipment in the hydrocracking plant. Due to the severe operational conditions, flange and nozzle cracking commonly occurs, especially for the seal groove between the flange and gasket. A cracked stainless flange is found in a hydrocracking reactor during parking and maintenance. Through a series of experiments including chemical composition, metallographic analysis, SEM and fracture analysis, the flange seal groove is analyzed. Under the long term operation at high temperature and high pressure, the σ phase is found in the flange material which will increase the cracking tendency. The hydrogen content measurement also proves that the material has the hydrogen embrittlement tendency. Hence, the combination of σ brittle phase and high stress causes the flange seal groove cracking. After cracking, hydrogen element enters the fracture, thus accelerating the crack growth. Therefore, in order to prevent the flange cracking, the assembly stress should be controlled in an appropriate range. If necessary, periodical inspection must be performed.
Development of the Buckling Evaluation Method for Large Scale Vessel by the Testing of Gr. 91 Vessel Subjected to Vertical and Horizontal Loading
Authors: Okafuji Takashi , Miura Kazuhiro , Sago Hiromi , Murakami Hisatomo , Ando Masanori , Miyazaki Masashi
Published: December 2020

Larger-diameter cylindrical vessels for commercial fast breeder reactors (FBRs) are planned to increase the electric generation capacity with thinner vessels compared to the existing ones. The modified 9Cr-1Mo steel (ASME Grade 91 steel) has high yield stress and low tangent modulus after yielding, and plans to be applied as well as austenitic stainless steel for vessels in existing FBR power plants. Although elasto-plastic axial compression, bending and shear buckling are expected to occur in vessels, the current buckling strength evaluation from the Japan Society of Mechanical Engineers (JSME) standard “Design and Construction for Nuclear Power Plants, Division 2 Fast Reactors” mainly focuses on plastic buckling of thick cylindrical vessels.

Seismic base isolation is being devised for next-generation FBR power plants by the increasing seismic design load in Japan. When a horizontal seismic base isolation design is adopted, cylindrical vessels are subject to cyclic vertical seismic load with long-period horizontal seismic wave. The deformation by cyclic vertical load reduces the buckling strength.

In this paper, we modified the existing buckling strength equations focusing on elasto-plastic axial compression, bending and shear buckling under cyclic axial load (hereinafter called “modified equations”), and confirmed their applicability through a series of elasto-plastic buckling analyses. We also conducted a series of buckling tests on Grade 91 steel vessels in the load regions where axial compression, bending and shear buckling interact, and where axial compression and bending buckling are dominant due to large vertical load. The buckling behavior and the buckling load estimated by the elasto-plastic buckling analysis considering the actual material stress–strain relationship and imperfections in the test vessel suitably agreed with corresponding test results in the load regions.
Results From Environmentally-Assisted Short Crack Fatigue Testing on Austenitic Stainless Steels
Authors: Coult Ben , Griffiths Adam , Beswick Jack , Gill Peter , Platts Norman , Smith Jean , Stevens Gary
Published: December 2020

The effect of environment on fatigue life is currently assessed using methods (such as NUREG/CR-6909) that may be excessively conservative when applied to plant components and loading transients. To reduce this conservatism, the ASME WG-EFEM has proposed the development of an improved assessment methodology for environmental fatigue based on a Total Life Prediction approach that would be adequately, but not excessively, conservative. Such an approach necessitates the development of analytical methods for the various stages of crack nucleation, short crack growth and long crack growth. Hence, there is a requirement to undertake testing within the short crack growth regime that would bridge the gap between fatigue nucleation and long crack growth (Paris Law) enabling better prediction of total life measured by fatigue endurance.

A test methodology has been developed by Wood to enable short crack growth testing with in-situ monitoring using DCPD. Testing has been undertaken in both high temperature air (300°C) and simulated end-of-cycle primary water chemistry at 300°C on cold-worked stainless steel specimens, which were subject to a range of load ratios and rise times. FEA modelling has been undertaken to determine the effective stress intensity factors applied under the loading conditions based on the specific material properties.

This paper presents the results from a testing program conducted with EPRI, to measure fatigue crack growth data for short cracks from 0.15 mm to 1.0 mm. Crack growth rates have been compared to those predicted in ASME, Code Case N-809 and results from material specific in-house testing to assist the understanding of the behaviour of mechanically short cracks.
Investigation of the Very High Cycle Fatigue (VHCF) Behavior of Austenitic Stainless Steels and Their Welds for Reactor Internals at Ambient Temperature and 300°C
Authors: Daniel T. , Smaga M. , Beck T. , Schopf T. , Stumpfrock L. , Weihe S. , Rudolph J.
Published: December 2020

The fatigue assessment of safety relevant components is of importance for ageing management with regard to safety and reliability of nuclear power plants.

For reactor internals, austenitic stainless steels are often used due to their excellent mechanical and technological properties as well as their corrosion resistance. During operation the material is subject to loadings in the Low Cycle Fatigue (LCF) regime due to start up and shut down procedures as well as high frequency loadings in the Very High Cycle Fatigue (VHCF) regime induced e.g. by stresses due to fast cyclic thermal fluctuations triggered by fluid dynamic processes. While the LCF behavior of austenitic steels is already well investigated the fatigue behavior in the VHCF regime has not been characterized in detail so far. Accordingly, the fatigue curves in the applicable international design codes have been extended by extrapolation to the range of highest load cycles (Fig. 1).

The aim of the cooperative project of the Institute of Materials Science and Engineering (WKK), Materials Testing Institute (MPA) Stuttgart and Framatome GmbH, Germany is to create a comprehensive database up to the highest load cycles N = 2·109 for austenitic stainless steels. For this fatigue tests on metastable austenitic steel AISI 347 / 1.4550 / X6CrNiNb1810 as well as austenitic welds (Fox SAS 2-A) were performed at an ultrasonic testing system at a test frequency of 20 000 Hz to realize acceptable testing times. In addition, an induction generator was implemented in the test system to investigate the influence of operation relevant temperature of 300 °C on the fatigue behavior. The ultrasonic testing system works under displacement control. Therefore, for reliable statements on fatigue life according NUREG/CR-6909 and using of S-N-curve (total-strain amplitude vs. cycle to failure) a fictitious-elastic and elastically-plastic numerical material model was used for calculation of total-strain amplitudes based on experimental data. The results shown, that at ambient temperature (AT) and 300 °C no specimen failure occurred in the VHCF regime for the base material as well as for the welds. Consequently, for these materials a real endurance limit exists.

Additionally, in a continuative test a specimen with a pre-autoclaving period in high temperature water (HTW) of 2500 hours was tested in air at a total strain amplitude of 0.1 % in the VHCF-regime up to number of cycle N = 109 using an ultrasonic fatigue testing system. The chemical composition of the HTW for the pre-autoclaving period is comparable to near operation conditions. Afterwards by using of scanning electron microscope no defects or cracks were detected in the oxide layer.
Stress Intensity Factor and Crack Opening Area of Circumferentially-Cracked Pipe Under Torsion Moment
Authors: Huang Yifan , Duan Xinjian
Published: December 2020

The deterministic leak-before-break (LBB) analysis and probabilistic fracture mechanics (PFM) assessment are two primary approaches for demonstrating extremely low probability of rupture of pressurized piping in the nuclear energy industry. Both stress intensity factor (SIF) and crack opening area (COA) are key components to the LBB and PFM assessments. Most of the studies and engineering practices focus on the SIF and COA due to axial tension, bending moment and internal pressure while limited investigations target on these parameters caused by torsion moment.

The objective of this study is to perform three-dimensional finite element analyses (3D FEA) to determine both SIF and COA for through-wall circumferential cracks in the pipe under bending or torsion moment. A range of normalized crack lengths (i.e. θ/π = 1/18 to 4/9) and three pipe radius over thickness ratios (i.e. Rm/t = 5, 10 and 25) are considered. Empirical solutions of the SIF for torsion loading as functions of crack geometry are developed. Comparisons for SIF regarding combined bending and torsion moments evaluated using code-specified solutions are presented. Finally, the COAs regarding the two loading modes are discussed. Such study is expected to be useful for both deterministic LBB analysis and PFM assessment of pressurized pipes.
Method for Comparison of Different Material Types in Environmental Fatigue Screening
Authors: Gray Mark A. , Oakman Jamie L. , Walker Adam P.
Published: December 2020

Requirements for plant license renewal require the evaluation and management of time limited aging analyses for the period of extended operation. These include metal fatigue analyses, with additional consideration for the effects of the reactor water environment. Current license renewal requirements for evaluation of time limited aging analyses for fatigue have extended environmentally assisted fatigue (EAF) considerations to additional locations beyond the originally prescribed NUREG/CR-6260 locations. These requirements have resulted in implementation of a screening process to identify locations that are potentially more limiting for further evaluation of EAF. The screening process includes comparisons of fatigue locations within common bases, including consideration of applicable system transients, rigor of analysis methods, and material types. To date, the United States Nuclear Regulatory Commission has only accepted EAF screening evaluation results based on comparisons within similar material types. However, there are conditions under which a comparison of locations with different material types is valid. This paper presents a basis to compare locations having different material types, to potentially reduce the number of leading (“sentinel”) locations in EAF screening evaluations. The methodology is described through a systematic approach and basis to determine when locations are more limiting with respect to EAF when different material types are compared.
Prediction of Collapse Load Reduction due to Non-Aligned Multiple Flaws
Authors: Iwamatsu Fuminori , Miyazaki Katsumasa , Saito Koichi
Published: December 2020

Fitness-for-Service (FFS) codes, such as ASME Boiler and Pressure Vessels Code, Section XI, have flaw characterization rules for evaluation of structural integrity. Since stress corrosion cracking (SCC) and thermal fatigue frequently cause multiple flaws, FFS codes should have proximity rules as a part of flaw characterization rules. The flaw characterization rules should consider fracture modes, such as brittle fracture, ductile fracture, and plastic collapse. Those in the current codes are not divided by the fracture modes. Especially, application of the current proximity rules to plastic collapse of non-aligned multiple flaws should be validated because there are few studies for this issue. Thus, fracture tests of flat plates with through-wall flaws and finite element analysis (FEA) were conducted for predicting collapse loads due to plastic collapse. A series of the fracture tests of flat plates with non-aligned two flaws has been conducted, and a trend between the load reduction and the flaw locations was shown from the results. This trend shows that the defined net-section for non-aligned multiple flaw dominate the collapse load. For the validation the trend shown by the fracture tests, FEA was performed for predicting the measured collapse load. Equivalent plastic strain around a flaw tip dominates a collapse behavior, and an equivalent plastic strain at collapse called as fracture strain was determined for FEA. The collapse loads predicted by the fracture strain are correspond with the test results for any flaw locations. FEA conditions can interpolate and cover a wide range of flaw locations conducted by the tests. The load ratios which represent effect of flaw interaction on a collapse load were estimated by parametric FEA. The ratios were mapped to investigate the trend of the effect on a collapse load. The mapped results show that the load ratio depends on a shorter flaw length of two flaws. This trend shown by the analysis results is corresponds with the fracture test results. These results are fundamental idea to make a flaw characterization rule in the FFS codes, such as ASME BPVC Section XI, for ductile fracture evaluation.
Crassoribatula biobioensis sp. nov. (Acari, Oribatida) from Chile, with transfer of the genus to Maudheimiidae (Ceratozetoidea)
Authors: Ermilov Sergey G.
Published: December 2020

The oribatid mite genus Crassoribatula is recorded in the Neotropical region for the first time. One new arboreal species—Crassoribatula biobioensis sp. nov.—is described from twigs of olivillo tree in Chile; it differs from the type species—Crassoribatula maculosa—by the length of exobothridial and notogastral setae. The tritonymphal instar of the new species is described (the first data on juveniles in this genus). The systematic placement of Crassoribatula is discussed, resulting in transfer from Oribatulidae (Oripodoidea) to Maudheimiidae (Ceratozetoidea). A revised generic diagnosis for Crassoribatula is presented.
A guide to acoustics healthcare guidelines
Authors: Bliefnick Jay
Published: December 2020

Over the past few decades a number of guidelines describing recommended acoustics performance have been developed for hospitals and healthcare environments. These include documents from the Federal Guidelines Institute (FGI), World Health Organization (WHO), ANSI/ASA, ASHRAE, and LEED. Each of these guidelines include numerous acoustical recommendations (some that even contradict one another), regarding such topics as background noise levels in patient rooms, sound isolation requirements, reverberation times, and speech privacy. These guidelines strive to improve the overall acoustical comfort within healthcare environments in addition to patient perception, as measured in surveys like the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS). In this project, the implementation of hospital guidelines in the United States was assessed, focusing on when and where specific guidelines were instituted, the impact these guidelines have had on acoustics performance, and what can be done to improve acoustics conditions within hospitals and healthcare environments across the country.
Exploratory analysis of noise reduction solutions in a psychiatric ward using beamforming techniques
Authors: Navvab Mojtaba
Published: December 2020

The world health organization recommendations related to a psychiatric ward for sound pressure level measurements overtime are not to exceed 30 and 35 dBA, respectively. However, no published study results since 1975 have reported full compliance within a hospital. Hospitals are a stressful work environment regardless of the noise level that averages between 53 and 58 dBA. Unique working solutions offered by design architects and insurance companies to reduce noise conditions in a physiological health facility are not transferable to psychiatric units that are operating as a behavioral health facility. This study reports on an exploratory analysis of the noise reduction strategies within a psychiatric ward. Architecturally and electronically implemented noise mitigation solutions are used to minimize noise annoyance, which is related to the noise sensitivity of the patient and staff. Sound mapping and noise source localization are conducted utilizing beamforming techniques. Onsite noise measurements in time and frequency domain provide design opportunities for isolating patient rooms from noise by the public and staff working areas. The impact of working solutions on speech privacy and annoyance is determined. The results contribute to a more extensive database and opportunities toward improvement in design guidelines for psychiatric wards and a positive influence on the hospital soundscape.
Acoustic characterization of the New England shelf break
Authors: Loranger Scott , Lavery Andone C.
Published: December 2020

The Southern New England shelf break is a dynamic region of the ocean; warm core rings shed by the Gulf stream, salt fingers, and intrusions all contribute to a complex spatiotemporally variable oceanographic environment. One of the most distinct features is the shelfbreak front where warm and salty deep water collides with lower density, colder and fresher shelf water. The meandering front coincides with the presence of a group ofstrong scatterers, believed to be fish with swim bladders, known to be present in the area. During the Office of Naval Research Sediment Characterization Experiment in 2017 acoustic backscatter from narrowband (18 and 38 kHz) and broadband (70–280 kHz) shipboard echo sounders detected the turbulent microstructure at the shelf break front. The sound speed, temperature, salinity, and density were inferred from the acoustic backscatter, and verified by CTD and expendable bathythermograph (XBT) casts. This method provides a more holistic view of the water masses at the shelfbreak front than is possible from CTD and XBT casts alone. The position of the strong scatterers in relation to the front was also characterized to elucidate the water masses and physical oceanographic processes that drive the distribution of the scatterers.
Complete radiation boundary conditions for acoustic waves
Authors: Hagstrom Thomas
Published: December 2020

The radiation of energy to the far field is a central feature of acoustics. As such, efficient, convergent domain truncation algorithms are a necessary component of any software for simulating acoustic waves in the time domain. Complete radiation boundary conditions are, in our view, an ideal solution to this problem. In particular, they are provably spectrally convergent, depending on parameters which can be chosen automatically to guarantee any required accuracy; as they directly approximate both propagating and evanescent modes, the computational boundary can be placed arbitrarily close to scatterers or other inhomogeneities. In this talk we will outline the theory behind the method for scattering and waveguide problems with a homogeneous far field, discuss the simple implementation of the method via the solution of a coupled system wave equations in a thin double absorbing boundary layer, and consider its application in more complex settings including advective acoustics, stratified media, and random media. Numerical experiments in three space dimensions using high-order methods will be shown.