bluuebunny/crossref_metadata_2025 huggingface dataset:
Crack Growth Evaluation of Remnant Cracks Underneath an Excavate and Weld Repair
Authors: Ku Francis H. , McCracken Steven L.
Published: October 2017

This paper presents a finite element analysis (FEA) based approach to perform crack growth evaluation of remnant cracks in a mockup with a partial arc excavate and weld repair (EWR). The partial arc EWR is a mitigation option to address stress corrosion cracking (SCC) in nuclear power plant piping systems. The mockup is a dissimilar metal weld (DMW) consisting of an SA-508 Class 3 low alloy steel forging buttered with Alloy 182 welded to a Type 316L stainless steel plate with Alloy 82/182 weld metal. This material configuration represents a typical DMW of original construction in a pressurized water reactor (PWR). To create a representative partial arc EWR application, the outer half of the DMW is excavated and repaired with Alloy 52M weld metal. The crack growth evaluation process presented herein represents an advanced method to evaluate the Alloy 82/182 remnant crack growth as required by ASME Code Case N-847 for implementing a partial arc EWR, which is currently being considered via letter ballot at ASME BPV Standards Committee XI. After the repair, any crack that remains in the Alloy 82/182 remnant and underneath the EWR needs to be evaluated for stress corrosion cracking (SCC) to assess its potential to grow beyond the EWR coverage area. Conventional fracture mechanics approach may not be suitable to evaluate such a remnant crack because of its close proximity to multiple materials of different mechanical properties and unconventional crack shape. In the crack growth evaluation, a crack that is reminiscent of a circumferential crack in a pipe, and a crack that is reminiscent of a laminar crack in a pipe are evaluated to predict the time for each of them to grow beyond the partial arc EWR coverage arc length. It is expected that the approach, analysis steps, calculation procedures presented in this paper will be applicable to analyzing a pipe geometry using realistic residual stresses and operating stresses for an EWR.
Flange Quality Investigation to Prevent Brittle Fracture
Authors: Zhu Sophia , Bouman Jaap , Raghu Damodaran
Published: October 2017

A quality investigation was done on ASTM A350 flanges after discovery of unauthorized repairs for a deepwater project in the Gulf of Mexico. The investigation also revealed low Charpy impact values which can potentially cause brittle fracture at low service temperatures. Therefore, additional flanges from the same supply chain (various manufacturers) were quarantined and tested by the destructive Charpy impact method as well as by the non-destructive Automated Ball Indentation (ABI) method. Based on the results of the quarantined flanges, the remaining flanges that were already installed were deemed fit for service. ABI method was evaluated regarding its capability of measuring fracture toughness non-destructively. Actions were taken by other Deepwater projects to prevent brittle fracture, in terms of material specification, supply chain management and material property verification.
A Screening Methodology to Rapidly Reduce ILI Data, Visualise and Determine Most Detrimental Defects in Pipelines
Authors: Larrosa Nicolas O. , Lopez-Crespo Pablo , Ainsworth Robert A.
Published: October 2017

The amount of data requiring detailed analysis from that obtained during in-line inspection (ILI)is reduced by a screening methodology. The methodology uses ILI outputs (dimensions of flaws, orientation and distance from starting point) to generate a visualisation of the pits within the pipeline, a ranking of pits in terms of sphericity (roundness) and depth, to evaluate pit density and generate the models for finite element analysis. The rendering tool allows a clearer view of defects within the pipelines and provides a simplified way to focus on critical pits. For a particular case of in-field data provided by BP, the number of pits in a 12-inch riser of 11 km length was reduced from 1750 obtained to 43, 15 or 4 requiring analysis, depending on the level of conservatism introduced by the analyst. The tool will allow Oil and Gas owners and operators to reduce the immense amount of data obtained during pigging to a much less time-consuming set for flaw assessment.
Engineering Process-Zone Model for Evaluation of Structural Strength of Fuel Channel Annulus Spacers in CANDU Nuclear Reactors
Authors: Scarth Douglas , Xu Steven , Liu Cheng
Published: October 2017

The core of a CANDU(1) (CANada Deuterium Uranium) pressurized heavy water reactor consists of a lattice of either 390 or 480 horizontal Zr-Nb pressure tubes, depending on the reactor design. These pressure tubes contain the fuel bundles. Each pressure tube is surrounded by a Zircaloy calandria tube that operates at a significantly lower temperature. Fuel channel annulus spacers maintain the annular gap between the pressure tube and calandria tube throughout the operating life. To meet this design requirement, annulus spacers must have adequate structural strength to carry the interaction loads imposed between the pressure tube and calandria tube. Crush tests that have been performed on specimens from as-received and ex-service Inconel X-750 alloy spacers have demonstrated that the structural strength of Inconel X-750 spacers has degraded with operating time due to irradiation damage. There was a need for an engineering model to predict the future maximum load carrying capacity of the spacer coils for use in Fitness-for-Service evaluations of spacer structural integrity. An engineering process-zone model has been developed and used to analyze the spacer crush test results, and provide predictions of the Inconel X-750 spacer coil future maximum load carrying capacities. The engineering process-zone model is described in this paper. The process-zone model is based on the strip-yield approach of a process zone with a uniform restraining stress representing the fracture region that is surrounded by elastic material.
Determination of the Gasket Stress Distribution
Authors: Schaaf Manfred
Published: October 2017

The European Standard EN 1591-1 is used for the calculation of bolted flanged joints, stress analysis as well as for tightness proofs. In this calculation procedure gasket characteristics according to EN 13555 are used to describe the mechanical and the tightening behavior of gasket materials.

With further developments in the calculation algorithm and the use of the realistic gasket behavior in the calculation more detailed results can be obtained, which are comparable to results obtained from Finite Element Analysis. The flange rotation and the resulting uneven gasket stress distribution in the radial direction during the assembly of the flanged joint is the fundamental principle in this development. The effective compressed gasket width has influence on the required gasket forces for the tightness proof as well as on the mechanical behavior of the flanged joint, and thus also on the stress analysis.

In this paper, the determination of the effective gasket width using a newly developed approach [1] is optimized and the verification of this approach with Finite Element Analysis for several different gasket materials and flange geometries is shown.
Dealloying of As-Welded Microstructures in Aluminum Bronzes in Essential Cooling Water Service
Authors: Kirchhofer Rita , Vaillancourt Henry , Garner Michael , Cipolla Russell C.
Published: October 2017

Dealloying of aluminum-bronze (Al-Brz) is a potential environmentally-induced degradation mechanism in piping systems and components exposed to marine, brackish, or raw water service. Examples of this form of degradation have been observed in ASME Code Class 3 Essential Cooling Water systems. The degradation mechanism is loss of material due to selective leaching (i.e., dealuminification) due to localized corrosion. The dealloying occurs in the eutectoid phase in binary alloys; the eutectoid consists of α + β or α + β/γ2, and is dependent on aluminum content of the alloy, cooling rate during fabrication/welding, and the presence of a local crevice for the corrosion process to concentrate. Cast components are susceptible to general dealloying but unlike them, weldments of wrought pipe have not exhibited the same extent of degradation. The dealloying process leaves micro-voids in the microstructure within the eutectoid. Leakage (weepage) will occur once dealloying has extended through the wall thickness via a network of porous transformed phase. The dealloying process also causes a reduction in mechanical strength and fracture toughness properties.

A detailed metallurgical evaluation has been completed to establish a fundamental understanding of the resistance of the pipe welds to dealloying that explains the better performance of the welds versus the castings. Factors affecting the dealloying susceptibility, such as aluminum and iron content, cooling rates during the solidification process, and the resulting microstructural differences were studied and evaluated. It was found that dealloying will not penetrate into the material unless a continuous network of susceptible microstructure is present.

The difference in susceptibility between castings and weldments to dealloying was also determined. The findings of this comparative evaluation were significant and are being used in the aging management program to justify continued use of aluminum bronze piping welds for extended service for both above ground and below ground (buried) piping systems.
Nuclear Power Plant Fires and Explosions: Part II — Hydrogen Ignition Overview
Authors: Leishear Robert A.
Published: October 2017

Major accidents that were affected by hydrogen fires and explosions included Chernobyl, Three Mile Island, and Fukushima Daiichi. Smaller piping explosions have occurred at Hamaoka and Brunsbüttel Nuclear Power Plants. An overview of pertinent topics is presented here to compare similarities and differences between these accidents.

In particular, a hydrogen ignition mechanism is presented here, where fluid transients, or water hammer, may cause pressures to compress flammable hydrogen gas in reactor systems. As the gas compresses, it heats to temperatures sufficient to cause autoignition, or dieseling. Autoignition then leads to fires or explosions in nuclear power plant systems.

To explain this evolving theory on hydrogen ignition during fires and explosions, various nuclear power plant hydrogen accidents require discussion. For example, Chernobyl explosions were unaffected by water hammer, while a Three Mile Island hydrogen fire was a direct result of water hammer following a reactor meltdown, and explosions that followed a meltdown at Fukushima Daiichi occurred during a water hammer event. Other piping damages also occurred during water hammer events. The primary purpose of this paper is to serve as a literature review of past accidents and to provide new insights into those accidents.

In short, what is known versus what is unknown is discussed here with respect to the ignition sources of nuclear power plant fires and explosions. How can nuclear power plant safety be assured unless previous fire and explosion causes are understood? Prior to this work, they were not understood.
Nuclear Power Plant Fires and Explosions: Part I — Plant Designs and Hydrogen Ignition
Authors: Leishear Robert A.
Published: October 2017

Requiring further investigation, hydrogen explosions and fires have occurred in several operating nuclear reactor power plants. Major accidents that were affected by hydrogen fires and explosions included Chernobyl, Three Mile Island, and Fukushima Daiichi. Smaller piping explosions have occurred at Hamaoka and Brunsbüttel Nuclear Power Plants. This paper is the first paper in a series of publications to discuss this issue. In particular, the different types of reactors that have a history of fires and explosions are discussed here, along with a discussion of hydrogen generation in commercial reactors, which provides the fuel for fires and explosions in nuclear power plants.

Overall, this paper is a review of pertinent information on reactor designs that is of particular importance to this multi-part discussion of hydrogen fires and explosions. Without a review of reactor designs and hydrogen generation, the ensuing technical discussions are inadequately backgrounded. Consequently, the basic designs of pressurized water reactors (PWR’s), boiling water reactors (BWR’s), and pressure-tube graphite reactors (RBMK) are discussed in adequate detail. Of particular interest, the Three Mile Island design for a PWR is presented in some detail.
Accelerometer-Assessed Physical Activity and Sedentary Time in Youth With Disabilities
Authors: Lobenius-Palmér Karin , Sjöqvist Birgitta , Hurtig-Wennlöf Anita , Lundqvist Lars-Olov
Published: October 2017

This study compared accelerometer-assessed habitual physical activity (PA), sedentary time, and meeting PA recommendations among 102 youth with disabilities (7–20 years) in four subgroups—physical/visual impairments, intellectual disability, autism spectrum disorders, and hearing impairment—and 800 youth with typical development (8–16 years). Low proportions of youth with disabilities met PA recommendations, and they generally were less physically active and more sedentary than youth with typical development. The hearing impairment and autism spectrum disorder groups were the most and least physically active, respectively. Older age and to some extent female sex were related to less PA and more sedentary time. Considering the suboptimal levels of PA in youth with disabilities, effective interventions directed at factors associated with PA among them are needed.
Globally threatened vertebrates on islands with invasive species
Authors: Spatz Dena R. , Zilliacus Kelly M. , Holmes Nick D. , Butchart Stuart H. M. , Genovesi Piero , Ceballos Gerardo , Tershy Bernie R. , Croll Donald A.
Published: October 2017

We identify the invasive species and biogeographic patterns on islands with 1189 highly threatened vertebrates.
Free-space propagation of high-dimensional structured optical fields in an urban environment
Authors: Lavery Martin P. J. , Peuntinger Christian , Günthner Kevin , Banzer Peter , Elser Dominique , Boyd Robert W. , Padgett Miles J. , Marquardt Christoph , Leuchs Gerd
Published: October 2017

This study of structured light’s propagation across a 1.6-km free-space link indicates that adaptations to models may be required.
Melanoma topology reveals a stem-like phenotype that promotes angiogenesis
Authors: Lee Junmin , Abdeen Amr A. , Hedhli Jamila , Wycislo Kathryn L. , Dobrucki Iwona T. , Fan Timothy M. , Dobrucki Lawrence W. , Kilian Kristopher A.
Published: October 2017

Melanoma topology promotes a stem cell phenotype with the propensity to facilitate new vessel growth.
A generative vision model that trains with high data efficiency and breaks text-based CAPTCHAs
Authors: George Dileep , Lehrach Wolfgang , Kansky Ken , Lázaro-Gredilla Miguel , Laan Christopher , Marthi Bhaskara , Lou Xinghua , Meng Zhaoshi , Liu Yi , Wang Huayan , Lavin Alex , Phoenix D. Scott
Published: October 2017

Computer or human?

Proving that we are human is now part of many tasks that we do on the internet, such as creating an email account, voting in an online poll, or even downloading a scientific paper. One of the most popular tests is text-based CAPTCHA, where would-be users are asked to decipher letters that may be distorted, partially obscured, or shown against a busy background. This test is used because computers find it tricky, but (most) humans do not. George
et al.
developed a hierarchical model for computer vision that was able to solve CAPTCHAs with a high accuracy rate using comparatively little training data. The results suggest that moving away from text-based CAPTCHAs, as some online services have done, may be a good idea.

Science
, this issue p.
eaag2612
Obstruction of pilus retraction stimulates bacterial surface sensing
Authors: Ellison Courtney K. , Kan Jingbo , Dillard Rebecca S. , Kysela David T. , Ducret Adrien , Berne Cecile , Hampton Cheri M. , Ke Zunlong , Wright Elizabeth R. , Biais Nicolas , Dalia Ankur B. , Brun Yves V.
Published: October 2017

Elucidating a bacterial sense of touch

Bacteria can adhere to surfaces within the host. This leads to tissue colonization, induction of virulence, and eventually the formation of biofilms—multicellular bacterial communities that resist antibiotics and clearance by the immune system (see the Perspective by Hughes and Berg). Hug
et al.
show that bacteria have a sense of touch that allows them to change their behavior rapidly when encountering surfaces. This tactile sensing makes use of the inner components of the flagellum, a rotary motor powered by proton motif force that facilitates swimming toward surfaces. Thus, the multifunctional flagellar motor is a mechanosensitive device that promotes surface adaptation. In complementary work, Ellison
et al.
elucidate the role of bacterial pili in a similar surface-sensing role.

Science
, this issue p.
531
, p.
535
; see also p.
446
The emperor’s new wardrobe: Rebalancing diversity of animal models in neuroscience research
Authors: Yartsev Michael M.
Published: October 2017

The neuroscience field is steaming ahead, fueled by a revolution in cutting-edge technologies. Concurrently, another revolution has been underway—the diversity of species utilized for neuroscience research is sharply declining, as the field converges on a few selected model organisms. Here, from the perspective of a young scientist, I naively ask: Is the great diversity of questions in neuroscience best studied in only a handful of animal models? I review some of the limitations the field is facing following this convergence and how these can be rectified by increasing the diversity of appropriate model species. I propose that at this exciting time of revolution in genetics and device technologies, neuroscience might be ready to diversify again, if provided the appropriate support.
Roads to riches or ruin?
Authors: Laurance William F. , Arrea Irene Burgués
Published: October 2017

Global infrastructure expansion must balance social benefits and environmental hazards
An interferon-independent lncRNA promotes viral replication by modulating cellular metabolism
Authors: Wang Pin , Xu Junfang , Wang Yujia , Cao Xuetao
Published: October 2017

Host RNA helps promote viral replication

Viruses exploit host metabolic networks for survival. Wang
et al.
identified a long noncoding RNA (lncRNA) that enhances replication of multiple viruses in both mouse and human cells (see the Perspective by Kotzin
et al
). The expression of this cytoplasmic lncRNA was induced by viruses and independent of type I interferon. The lncRNA directly bound to and stimulated the metabolic enzyme glutamic-oxaloacetic transaminase. This viral strategy may have relevance for clinical diseases involving metabolic dysfunction and viral infection.

Science
, this issue p.
1051
; see also p.
993
Ethics of maternal vaccination
Authors: Chamberlain A. T. , Lavery J. V. , White A. , Omer S. B.
Published: October 2017

Involvement of women is critical in establishing guidelines
Atomic model for the dimeric F
O
region of mitochondrial ATP synthase
Authors: Guo Hui , Bueler Stephanie A. , Rubinstein John L.
Published: October 2017

How protons power rotation

Synthesis of adenosine triphosphate (ATP) in mitochondria is accomplished by a large molecular machine, the F
1
F
O
ATP synthase. Proton translocation across the F
O
region that spans the mitochondrial inner membrane drives ATP synthesis in the F
1
region through a rotational mechanism. Guo
et al.
present a high-resolution structure of the dimeric F
O
complex from
Saccharomyces cerevisiae
, determined by electron microscopy. The structure gives insights into how proton translocation powers rotation and suggests how F
O
dimers bend the membrane to give mitochondria their characteristic cristae.

Science
, this issue p.
936
Plasticity of the
MFS1
Promoter Leads to Multidrug Resistance in the Wheat Pathogen
Zymoseptoria tritici
Authors: Omrane Selim , Audéon Colette , Ignace Amandine , Duplaix Clémentine , Aouini Lamia , Kema Gert , Walker Anne-Sophie , Fillinger Sabine
Published: October 2017

Disease control through fungicides remains an important means to protect crops from fungal diseases and to secure the harvest. Plant-pathogenic fungi, especially
Zymoseptoria tritici
, have developed resistance against most currently used active ingredients, reducing or abolishing their efficacy. While target site modification is the most common resistance mechanism against single modes of action, active efflux of multiple drugs is an emerging phenomenon in fungal populations reducing additionally fungicides’ efficacy in multidrug-resistant strains. We have investigated the mutations responsible for increased drug efflux in
Z. tritici
field strains. Our study reveals that three different insertions of repeated elements in the same promoter lead to multidrug resistance in
Z. tritici
. The target gene encodes the membrane transporter MFS1 responsible for drug efflux, with the promoter inserts inducing its overexpression. These results underline the plasticity of repeated elements leading to fungicide resistance in
Z. tritici
.
Sleep disturbance in family caregivers of children who depend on medical technology
Authors: Keilty Krista , Cohen Eyal , Spalding Karen , Pullenayegum Eleanor , Stremler Robyn
Published: October 2017

Objectives

Family caregivers of children who depend on medical technology (CMT) provide highly skilled care up to 24 hours per day. Sleep disruption places family caregivers at risk for poor health and related outcomes that threaten their long-term caregiving capacity. Few studies exist that have measured sleep in family caregivers, and most have relied entirely on subjective measures.

Methods

In a prospective cohort study, family caregivers of CMT (n=42) and caregivers of healthy children (n=43) were recruited. Actigraphy data and a concurrent sleep diary were collected for 6 days/7 nights. Measures of sleep quality, depression, sleepiness, fatigue and quality of life were also administered.

Results

Family caregivers of CMT averaged fewer hours of sleep per night (mean (SD)) (6.56 ± 1.4 vs 7.21 ± 0.6, p=0.02) of poorer quality (7.75 ± 2.9 vs 5.45 ± 2.8, p<0.01) than the control group. Three times as many family caregivers of CMT scored in the range for significant depressive symptomatology (12(33%) vs 4(10%), p=0.01) and experienced excessive daytime sleepiness (16(38%) vs 5(12%), p<0.01). Fatigue was also more problematic among family caregivers of CMT (22.12 ± 9.1 vs 17.44 ± 9.0, p=0.02).

Conclusions

Family caregivers of CMT are at risk of acute and chronic sleep deprivation, psychological distress and impaired daytime function that may threaten their capacity for sustained caregiving. Family caregivers of CMT may be important targets for screening for sleep disorders and the development of novel sleep-promoting interventions.
Compliance with nutrition screening in a children’s hospital
Authors: Marino Luise V , Beattie Robert Mark
Published: October 2017

Introduction

There has been an increased emphasis on the nutritional care of children in hospital with the recognition that those admitted to hospital, particularly with chronic conditions, are at significant nutrition risk. However, although nutrition risk screening tools (NRST) are widely used in acute hospital settings compliance with their use is poorly reported.

Methods

One-day cross-sectional audit of anthropometry/NRST records, Southampton Children’s Hospital. Inclusion criteria were all in-patients present on the ward between 8 am and 4 pm. Comparison was made with previous data.

Results

One hundred and thirteen records were reviewed. Anthropometric measures; weight recorded in 96.4% length/height recorded in 64% . This reflects a significant improvement on previous length/height data of 19%. Compliance with NRST was poor; only 17% of records were completed.

Conclusion

Compliance with basic anthropometry was high and better than previously reported although use of nutritional screening tools was poor. This raises questions about the usefulness of current tools in clinical practice and whether measurement of height, weight and assessment of intake and nutrition risk may be more appropriate.
Comparative analysis of autofluorescence and OCT angiography in Stargardt disease
Authors: Guduru Abhilash , Lupidi Marco , Gupta Arushi , Jalali Subhadra , Chhablani Jay
Published: October 2017

Aims

To characterise the vasculature of the retina in patients with Stargardt disease (STGD) using optical coherence tomography angiography (OCTA) and to compare these functional findings with fundus autofluorescence (FAF) imaging.

Methods

This observational study included consecutive patients with STGD. The choriocapillaris (CC) layer was analysed on OCTA and retinal pigment epithelium (RPE) changes were assessed on FAF. Areas of CC and RPE impairment were quantified and correlated.

Results

Twenty-two patients suffering from different stages of STGD were enrolled. OCTA revealed a vascular rarefaction with vascular prominence in 15 (35%) eyes while the remaining cases had pure vascular rarefaction. On FAF imaging, 25 (58%) eyes had a peripapillary halo, a hypofluorescent lesion in foveal area and the presence of both hypofluorescent and hyperfluorescent changes. On FAF imaging, the average area of RPE impairment was 6.7±4.4 mm2 while on OCTA a hypointense area of 4.2±3.6 mm2 was shown at the level of the CC layer. Mann-Whitney U test showed a statistically significant difference in terms of lesion extension between these two findings (p=0.004).

Conclusion

RPE damage on FAF appears to be significantly larger than CC layer vessel loss on OCTA, which suggests that RPE damage might precede that of CC.
Sport, sex and age increase risk of illness at the Rio 2016 Summer Paralympic Games: a prospective cohort study of 51 198 athlete days
Authors: Derman Wayne , Schwellnus Martin P , Jordaan Esme , Runciman Phoebe , Blauwet Cheri , Webborn Nick , Lexell Jan , Van de Vliet Peter , Tuakli-Wosornu Yetsa , Kissick James , Stomphorst Jaap
Published: October 2017

Objective

To describe the epidemiology of illness at the Rio 2016 Summer Paralympic Games.

Methods

A total of 3657 athletes from 78 countries, representing 83.5% of all athletes at the Games, were monitored on the web-based injury and illness surveillance system (WEB-IISS) over 51 198 athlete days during the Rio 2016 Summer Paralympic Games. Illness data were obtained daily from teams with their own medical support through the WEB-IISS electronic data capturing systems.

Results

The total number of illnesses was 511, with an illness incidence rate (IR) of 10.0 per 1000 athlete days (12.4%). The highest IRs were reported for wheelchair fencing (14.9), para swimming (12.6) and wheelchair basketball (12.5) (p<0.05). Female athletes and older athletes (35–75 years) were also at higher risk of illness (both p<0.01). Illnesses in the respiratory, skin and subcutaneous and digestive systems were the most common (IRs of 3.3, 1.8 and 1.3, respectively).

Conclusion

(1) The rate of illness was lower than that reported for the London 2012 Summer Paralympic Games; (2) the sports with the highest risk were wheelchair fencing, para swimming and wheelchair basketball; (3) female and older athletes (35–75 years) were at increased risk of illness; and (4) the respiratory system, skin and subcutaneous system and digestive system were most affected by illness. These results allow for comparison at future Games.
Epidemiology of imaging-detected bone stress injuries in athletes participating in the Rio de Janeiro 2016 Summer Olympics
Authors: Hayashi Daichi , Jarraya Mohamed , Engebretsen Lars , D Crema Michel , W Roemer Frank , Skaf Abdalla , Guermazi Ali
Published: October 2017

Background

Bone stress injuries are common in high-level athletics.

Aim

To describe the demographics, frequency and anatomical location of stress injuries (ie, stress reaction and stress fractures) in athletes at the Rio de Janeiro 2016 Summer Olympic Games.

Methods

We recorded all sports injuries at the Rio de Janeiro 2016 Summer Olympics reported by the National Olympic Committee (NOC) medical teams and in the polyclinic and medical venues. Imaging was performed through the official IOC clinic within the Olympic Village, using digital X-ray cameras and 3T and 1.5T magnetic resonance (MR) scanners. Images were read centrally and retrospectively by musculoskeletal radiologists with expertise in sports injuries.

Results

11 274 athletes (5089 women (45%), 6185 men (55%)) from 207 NOCs participated in the study. 1101 injuries were reported. Imaging revealed 9 stress fractures (36%) and 16 stress reactions (64%) in 18 female and 7 male athletes (median age 25 years, age range 18–32). Stress injuries were mostly in the lower extremities (84%), particularly tibia (44%) and metatarsals (12%), with two in the lumbar spine (8%). Stress injuries were most common in track and field athletes (44%) followed by volleyball players (16%), gymnastics (artistic) (12%) and other type of sports.

Conclusions

Twenty-five bone stress injuries were reported, more commonly in women, mostly in the lower extremities and most commonly in track and field athletes. Our study demonstrates the importance of early imaging with MRI to detect stress reactions before they can progress to stress fractures.
Systematic review of interventions for improving the performance of community health workers in low-income and middle-income countries
Authors: Ballard Madeleine , Montgomery Paul
Published: October 2017

Objective

To systematically review and critically appraise the evidence for the effects of interventions to improve the performance of community health workers (CHWs) for community-based primary healthcare in low- and middle-income countries.

Design

Systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Methods

19 electronic databases were searched with a highly sensitive prespecified strategy and the grey literature examined, completed July 2016. Randomised controlled trials evaluating interventions to improve CHW performance in low- and middle-income countries were included and appraised for risk of bias. Outcomes were biological and behavioural patient outcomes (primary), use of health services, quality of care provided by CHWs and CHW retention (secondary).

Results

Two reviewers screened 8082 records; 14 evaluations were included. Due to heterogeneity and lack of clear outcome data, no meta-analysis was conducted. Results were presented in a narrative summary. The review found one study showing no effect on the biological outcomes of interest, though these moderate quality data may not be indicative of all biological outcomes. It also found moderate quality evidence of the efficacy of performance improvement interventions for (1) improving behavioural outcomes for patients, (2) improving use of services by increasing the absolute number of patients who access services and, perhaps, better identifying those who would benefit from such services and (3) improving CHW quality of care in terms of upstream measures like completion of prescribed activities and downstream measures like adherence to treatment protocols. Nearly half of studies were compound interventions, making it difficult to isolate the effects of individual performance improvement intervention components, though four specific strategies pertaining to recruitment, supervision, incentivisation and equipment were identified.

Conclusions

Variations in recruitment, supervision, incentivisation and equipment may improve CHW performance. Practitioners should, however, assess the relevance and feasibility of these strategies in their health setting prior to implementation. Component selection experiments on a greater range of interventions to improve performance ought to be conducted.
Occupational exposures and mammographic density in Spanish women
Authors: Lope Virginia , García-Pérez Javier , Pérez-Gómez Beatriz , Pedraza-Flechas Ana María , Alguacil Juan , González-Galarzo Mª Carmen , Alba Miguel Angel , van der Haar Rudolf , Cortés-Barragán Rosa Ana , Pedraz-Pingarrón Carmen , Moreo Pilar , Santamariña Carmen , Ederra María , Vidal Carmen , Salas-Trejo Dolores , Sánchez-Contador Carmen , Llobet Rafael , Pollán Marina
Published: October 2017

Objectives

The association between occupational exposures and mammographic density (MD), a marker of breast cancer risk, has not been previously explored. Our objective was to investigate the influence of occupational exposure to chemical, physical and microbiological agents on MD in adult women.

Methods

This is a population-based cross-sectional study based on 1476 female workers aged 45–65 years from seven Spanish breast cancer screening programmes. Occupational history was surveyed by trained staff. Exposure to occupational agents was assessed using the Spanish job-exposure matrix MatEmESp. Percentage of MD was measured by two radiologists using a semiautomatic computer tool. The association was estimated using mixed log-linear regression models adjusting for age, education, body mass index, menopausal status, parity, smoking, alcohol intake, type of mammography, family history of breast cancer and hormonal therapy use, and including screening centre and professional reader as random effects terms.

Results

Although no association was found with most of the agents, women occupationally exposed to perchloroethylene (eβ=1.51; 95% CI 1.04 to 2.19), ionising radiation (eβ=1.23; 95% CI 0.99 to 1.52) and mould spores (eβ=1.44; 95% CI 1.01 to 2.04) tended to have higher MD. The percentage of density increased 12% for every 5 years exposure to perchloroethylene or mould spores, 11% for every 5 years exposure to aliphatic/alicyclic hydrocarbon solvents and 3% for each 5 years exposure to ionising radiation.

Conclusions

Exposure to perchloroethylene, ionising radiation, mould spores or aliphatic/alicyclic hydrocarbon solvents in occupational settings could be associated with higher MD. Further studies are needed to clarify the accuracy and the reasons for these findings.
Tricks of the trade: time management tips for newly qualified doctors
Authors: Offiah Gozie , Doherty Eva
Published: October 2017

Background

The transition from medical student to doctor is an important milestone. The discovery that their time is no longer their own and that the demands of their job are greater than the time they have available is extremely challenging.

Methods

At a recent surgical boot camp training programme, 60 first-year surgical trainees who had just completed their internship were invited to reflect on the lessons learnt regarding effective time management and to recommend tips for their newly qualified colleagues. They were asked to identify clinical duties that were considered urgent and important using the time management matrix and the common time traps encountered by newly qualified doctors.

Results

The surgical trainees identified several practical tips that ranged from writing a priority list to working on relationships within the team. These tips are generic and so applicable to all newly qualified medial doctors.

Potential implication

We hope that awareness of these tips from the outset as against learning them through experience will greatly assist newly qualified doctors.
Complete genome sequence of Enterobacter cloacae R11 reveals multiple genes potentially associated with high-level polymyxin E resistance
Authors: Zhong Chuanqing , Zhang Chao , Fu Jiafang , Chen Wenbing , Jiang Tianyi , Cao Guangxiang
Published: October 2017

Enterobacter cloacae strain R11 is a multidrug-resistant bacterium isolated from sewage water near a swine feedlot in China. Strain R11 can survive in medium containing up to 192 μg/mL polymyxin E, indicating a tolerance for this antibiotic that is significantly higher than that reported for other gram-negative bacteria. In this study, conjugation experiments showed that partial polymyxin E resistance could be transferred from strain R11 to Escherichia coli strain 25922, revealing that some genes related to polymyxin E resistance are plasmid-based. The complete genome sequence of this strain was determined, yielding a total of 4 993 008 bp (G+C content, 53.15%) and 4908 genes for the circular chromosome and 4 circular plasmids. Genome analysis revealed a total of 73 putative antibiotic resistance genes, including several polymyxin E resistance genes and genes potentially involved in multidrug resistance. These data provide insights into the genetic basis of the polymyxin E resistance and multidrug resistance of E. cloacae.
Gravitational quanta and unification
Authors: Cooperstock F. I.
Published: October 2017

A major issue that has challenged physics is the goal of bringing gravity into a complete unification of the interactions and the quantization of gravity. We build upon the appreciation that electromagnetic waves are also gravitational waves because they transport local spacetime curvature. Logical steps lead us to appreciate the totality of the traditional quantized particles in nature as gravitational quanta. Thus, our present particle physics model is seen to be unified with the gravitational interaction. Whether there remains a scope for the existence of a spin-2 graviton in vacuum is brought into question by our invariant energy construct centered upon the Ricci tensor. We suggest that this construct holds the key to ultra-strong gravity’s essential role in quantization.
Gravitation as a source of decoherence
Authors: Das Saurya , Robbins Matthew P. G. , Vagenas Elias C.
Published: October 2017

It is believed that classical behavior emerges in a quantum system due to decoherence. It has also been proposed that gravity can be a source of this decoherence. We examine this in detail by studying a number of quantum systems, including ultrarelativistic and nonrelativistic particles, at low and high temperatures in an expanding universe, and show that this proposal is valid for a large class of quantum systems.
Free Vibration of MDOF Systems with Nonperiodically Time-Varying Mass
Authors: Hozhabrossadati Seyed Mojtaba , Sani Ahmad Aftabi
Published: October 2017

This paper deals with the free vibration response of MDOF mass-spring systems with time-variable mass and constant stiffness. To show the necessity of this study, a review on the related published articles is presented. After formulating the governing initial value problem which is a coupled system of differential equations with variable coefficients, the differential transform method (DTM) is employed to obtain an analytical solution. The proposed solutions are verified against exact results available in the literature. It is demonstrated that the effect of time-variable mass is equivalent to viscous damping. This viscous damping can be positive or negative depending on the sign of the mass change rate. This role is thoroughly investigated via numerical examples.
Radicability condition on GLn(D)
Authors: Fallah-Moghaddam R. , Moshtagh H.
Published: October 2017

Given an indivisible field [Formula: see text], let [Formula: see text] be a finite dimensional noncommutative [Formula: see text]-central division algebra. It is shown that if [Formula: see text] is radicable, then [Formula: see text] is the ordinary quaternion division algebra and [Formula: see text] is divisible. Also, it is shown that when [Formula: see text] is a field of characteristic zero and [Formula: see text], then [Formula: see text] is radicable if and only if for any field extension [Formula: see text] with [Formula: see text], [Formula: see text] is divisible.
Raychaudhuri equation in the Finsler–Randers space-time and generalized scalar-tensor theories
Authors: Stavrinos Panayiotis C. , Alexiou Maria
Published: October 2017

In this work, we obtain the Raychaudhuri equations for various types of Finsler spaces as the Finsler–Randers (FR) space-time and in a generalized geometrical structure of the space-time manifold which contains two fibers that represent two scalar fields [Formula: see text]. We also derive the Klein–Gordon equation for this model. In addition, the energy conditions are studied in a FR cosmology and are correlated with FRW model. Finally, we apply the Raychaudhuri equation for the model [Formula: see text], where M is a FRW-space-time.
Classification of Einstein equations with cosmological constant in warped product space-time
Authors: Gholami F. , Haji-Badali A. , Darabi F.
Published: October 2017

We classify all warped product space-times in three categories as (i) generalized twisted product structures, (ii) base conformal warped product structures and (iii) generalized static space-times and then we obtain the Einstein equations with the corresponding cosmological constant by which we can determine uniquely the warp functions in these warped product space-times.
Biological evaluation of a Porphyrin-SPION nanoconjugate as an antimicrobial magnetic photosensitizer
Authors: Thandu Merlyn M. , Cavalli Silvia , Rossi Giada , Rizzardini Claudia B. , Goi Daniele , Comuzzi Clara
Published: October 2017

The present work describes the use of a magnetic porphyin (5-(4-carboxy-phenyl)-10,15,20-triphenyl-21H, 23H-porphyrin TPP) nanoconjugate (SPION-TPP) for destroying pathogenic bacteria followed by the recovery of the magnetic photosensitizer. SPION-TPP was tested for its activity against two different gram-positive bacterial strains (Staphylococcus aureus and Steptoccoccus mutans). It is observed that SPION-TPP at a very low concentration of 0.5 [Formula: see text]M is effective in destroying gram-positive bacteria (10[Formula: see text]–10[Formula: see text] CFU ml[Formula: see text] S. aureus with several orders reduction and few orders in S. mutans. The aim of this work is to combine photoactivity against microorganisms imparted by the photosensitizer with the possibility of recovering the nanoconstruct with magnets for disposal/reuse.
Transmission Adaptation for Battery-Free Relaying
Authors: Wang Zejue , Li Hongjia , Hu Dan , Ci Song
Published: October 2017

Energy harvesting (EH)–enabled relaying has attracted considerable attention as an effective way to prolong the operation time of energy-constrained networks and extend coverage beside desired survivability and rate of transmission. In related literature, the Harvest-Store-Use (HSU) model is usually utilized to describe the energy flow behavior of the EH system. However, the half-duplex (HD) constraint of HSU that harvested energy can only be used after being temporally stored in energy buffer may reduce effective transmission time. Thus, we first construct the full-duplex (FD) energy flow behavior model of the EH system where the harvested energy can be tuned to power load and being stored simultaneously. The FD model is then proved to be equivalent with the HSU model when time interval is small enough. Considering some key physical variabilities, for example, the wireless channel and the amount of harvested energy, the transmission adaptation problem for multiple relays embedded with FD EH systems is formulated with the objective to improve the utilization of the harvested energy. We tackle the problem by using a centralized optimization algorithm by jointly tuning the factors, including power control for source and relay nodes, relay selection and dynamic switching among four relay transmission mode, namely HD amplify-and-forward (AF), HD decode-and-forward (DF), FD AF, and FD DF. The centralized optimization algorithm is proposed on the basis of dual decomposition and serves as a benchmark. To enable relays to individually make their own decisions, a distributed algorithm with relatively higher complexity is given by using consensus optimization in conjunction with the alternating direction method of multipliers, and a sub-optimal algorithm with low complexity is provided. The proposed algorithms are shown to have good performance via simulations for a range of different EH rates and prediction errors.
Towards Cyber-Physical Systems Design for Structural Health Monitoring
Authors: Bhuiyan Md Zakirul Alam , Wu Jie , Wang Guojun , Cao Jiannong , Jiang Wenjun , Atiquzzaman Mohammed
Published: October 2017

Large civil structures, such as bridges, buildings, and aerospace vehicles form the backbone of our society are critical to some catastrophic events such as damage. Wired sensor networks are usually adopted for structural health monitoring (SHM) applications. This is also an important Smart City application. Recent wireless sensor networks (WSNs) technology promises the eventual ability to cover such a structure and continuously monitor its health. However, researchers from both engineering and computer science domains face numerous hurdles, such as application-specific requirements, in reaching this goal. These hurdles have a cumulative effect on severely resource-constrained WSNs. This article provides a comprehensive investigation of WSN-based SHM applications with an emphasis on networking perspectives to get insights into a cyber-physical system (CPS) design.
First
, we provide the SHM philosophy and conduct extensive comparative studies regarding various aspects of benefits and hurdles of going wireless for SHM.
Second
, we propose a taxonomy of SHM techniques and their applicability to WSNs.
Third
, we show a transition from the WSN-based SHM towards the CPS design, expecting that such a design will mitigate WSN resource constraints and satisfy SHM application-specific requirements to a great extent. For each of these, we discuss a surge of existing schemes with an emphasis on limitations of the state-of-the-art, and we point out open issues.
Finally
, we propose a series of design guidelines for a potential CPS. This article will help both engineering and computer science domain researchers/engineers and respective communities in designing future CPS to ensure the economic benefit and public safety in functioning civil structures.
Healthcare robotics
Authors: Riek Laurel D.
Published: October 2017

Healthcare robotics can provide health and wellness support to billions of people.
Spider Covers for Prize-Collecting Network Activation Problem
Authors: Fukunaga Takuro
Published: October 2017

In the network activation problem, each edge in a graph is associated with an activation function that decides whether the edge is activated from weights assigned to its end nodes. The feasible solutions of the problem are node weights such that the activated edges form graphs of required connectivity, and the objective is to find a feasible solution minimizing its total weight. In this article, we consider a prize-collecting version of the network activation problem and present the first nontrivial approximation algorithms. Our algorithms are based on a new linear programming relaxation of the problem. They round optimal solutions for the relaxation by repeatedly computing node weights activating subgraphs, called spiders, which are known to be useful for approximating the network activation problem. For the problem with node-connectivity requirements, we also present a new potential function on uncrossable biset families and use it to analyze our algorithms.