bluuebunny/crossref_metadata_2025 huggingface dataset:
Velocity-Domain Motion Quality Measures for Surgical Performance Evaluation and Feedback
Authors: Murali Barathwaj , Belvroy Viony M. , Pandey Shivam , Bismuth Jean , Byrne Michael D. , O'Malley Marcia K.
Published: December 2020

Endovascular navigation proficiency requires a significant amount of manual dexterity from surgeons. Objective performance measures derived from endovascular tool tip kinematics have been shown to correlate with expertise; however, such metrics have not yet been used during training as a basis for real-time performance feedback. This paper evaluates a set of velocity-based performance measures derived from guidewire motion to determine their suitability for online performance evaluation and feedback. We evaluated the endovascular navigation skill of 75 participants using three metrics (spectral arc length, average velocity, and idle time) as they steered tools to anatomical targets using a virtual reality simulator. First, we examined the effect of navigation task and experience level on performance and found that novice performance was significantly different from intermediate and expert performance. Then we computed correlations between measures calculated online and spectral arc length, our “gold standard” metric, calculated offline (at the end of the trial, using data from the entire trial). Our results suggest that average velocity and idle time calculated online are strongly and consistently correlated with spectral arc length computed offline, which was not the case when comparing spectral arc length computed online and offline. Average velocity and idle time, both time-domain based performance measures, are therefore more suitable measures than spectral arc length, a frequency-domain based metric, to use as the basis of online performance feedback. Future work is needed to determine how to best provide real-time performance feedback to endovascular surgery trainees based on these metrics.
Reliable Calculation of Thermoacoustic Instability Risk Using an Imperfect Surrogate Model
Authors: Guo Shuai , Silva Camilo F. , Polifke Wolfgang
Published: December 2020

One of the fundamental tasks in performing robust thermoacoustic design of gas turbine combustors is calculating the modal instability risk, i.e., the probability that a thermoacoustic mode is unstable, given various sources of uncertainty (e.g., operation or boundary conditions). To alleviate the high computational cost associated with conventional Monte Carlo simulation, surrogate modeling techniques are usually employed. Unfortunately, in practice, it is not uncommon that only a small number of training samples can be afforded for surrogate model training. As a result, epistemic uncertainty may be introduced by such an “inaccurate” model, provoking a variation of modal instability risk calculation. In the current study, using Gaussian process (GP) as the surrogate model, we address the following two questions: First, how to quantify the variation of modal instability risk induced by the epistemic surrogate model uncertainty? Second, how to reduce the variation of risk calculation given a limited computational budget for the surrogate model training? For the first question, we leverage on the Bayesian characteristic of the GP model and perform correlated sampling of the GP predictions at different inputs to quantify the uncertainty of risk calculation. We show how this uncertainty shrinks when more training samples are available. For the second question, we adopt an active learning strategy to intelligently allocate training samples such that the trained GP model is highly accurate particularly in the vicinity of the zero growth rate contour. As a result, a more accurate and robust modal instability risk calculation is obtained without increasing the computational cost of surrogate model training.
Effect of Cold-Rolling on Hydrogen Diffusion and Trapping in X70 Pipeline Steel
Authors: Thomas Alen , Szpunar Jerzy A.
Published: December 2020

In this investigation, we prepared samples with five different grain misorientations by cold-rolling an X70 pipeline steel plate. The hydrogen permeation and hydrogen visualization experiments were used to compute the diffusion parameters and to reveal the diffusion path in steel samples. The dual-polarized permeation experiment allowed us to show that permeability and effective diffusion coefficient were decreased with an increase in misorientation. Hence, the total and irreversible trapping sites were also raised with the extent of deformation in the steel. On the other hand, the visualization study permitted us to show that hydrogen diffusion intensity changes within the microstructure. The diffusion intensity increases in the order of non-deformed grains, grain boundaries, and deformed grains with deformed grains as the easiest path for hydrogen diffusion.
Influences of Iteration Details on Flow Continuities of Numerical Solutions to Isothermal Elastohydrodynamic Lubrication With Micro-Cavitations
Authors: Liu Shuangbiao , Qiu Liangwei , Wang Zhijian , Chen Xiaoyang
Published: December 2020

Studying elastohydrodynamic lubrication (EHL) of line contacts involving micro-cavitations, this paper examines various numerical solutions with a focus on their explicit flow continuities from inlet to exit. For the first time, influences of relaxation details, error controls, differential schemes, and mesh densities on flow continuity in EHL are revealed systemically. Furthermore, hybrid relaxation factors are introduced, the line relaxation is enabled with earlier boundary-condition enforcement, and a typical iteration process is updated with a three-in-one iteration control. Such a process is further integrated with two different starvation/cavitation treatments: one explicitly adjusts reformation locations, and the other uses a fractional film content parameter to adjust the Couette term originated by Bayada et al. The mass conservation results for problems with multiple micro-cavitations occurring inside the lubrication region are compared, and flow curves clearly demonstrate satisfactory continuities. These insights are beneficial for EHL simulations.
The Cost on System Performance of Requirements on Differentiable Variables
Authors: Hazelrigg George A. , Stolfi Philip
Published: December 2020

System design is commonly thought of as a process of maximizing a design objective subject to constraints, among which are the system requirements. Given system-level requirements, a convenient management approach is to disaggregate the system into subsystems and to “flowdown” the system-level requirements to the subsystem or lower levels. We note, however, that requirements truly are constraints, and they typically impose a penalty on system performance. Furthermore, disaggregation of the system-level requirements into the flowdown requirements creates added sets of constraints, all of which have the potential to impose further penalties on overall system performance. This is a highly undesirable effect of an otherwise beneficial system design management process. This article derives conditions that may be imposed on the flowdown requirements to assure that they do not penalize overall system performance beyond the system-level requirement.
A Symmetric Multichamber Hydraulic Cylinder With Variable Piston Area: An Approach to Compact and Efficient Electrohydrostatic Actuation
Authors: Bartlett Harrison L.
Published: December 2020

This paper presents an approach for designing symmetric (effective cylinder area during extension is the same as that during retraction) multichamber cylinders with discretely variable piston area. The design methodology is presented in a generalizable manner and is demonstrated on an example five-chamber cylinder design. A method for finding symmetric multichamber cylinder configurations from a given cylinder topology is presented, and subsequently, a method for discretely varying the effective piston area is developed, subject to a cylinder symmetry constraint. Furthermore, an algorithm is presented to optimally switch the effective cylinder area of an electrohydrostatic actuation system either to minimize the magnitude of motor torque or to minimize resistive power losses in the system. Additionally, a method for optimizing standard (constant area) hydraulic cylinders to minimize motor torque magnitude or resistive power losses is presented. These methods are then demonstrated on an example electrohydrostatic actuation system via simulation. Results indicate that this multichamber cylinder approach with discretely variable piston area may allow for the design of compact and efficient actuators relative to standard methods.
Design of Bionic Foldable Wing Mimicking the Hind Wings of theC. BuquetiBamboo Weevil
Authors: Li Xin , Guo Ce , Ma Yaopeng , Zheng Yu
Published: December 2020

The bamboo weevil, Cyrtotrachelus buqueti, has excellent flight ability and strong environmental adaptability. When it flies, its fore wings and hind wings are unfolded, whereas when it crawls, its fore wings are closed, and its flexible hind wings are regularly folded under the fore wings. In this paper, the hind wing folding/unfolding pattern of C. buqueti is analyzed and a new bionic foldable wing with rigid–flexible coupling consisting of a link mechanism and a wing membrane is constructed. The movement of the link at the wing base mimics the contraction of a muscle in the thorax that triggers scissor-like motion and the deployment of the veins. Elastic hinges are used to mimic the rotational motion of the wing base and the vein joints. The static/dynamic characteristics of bionic foldable wings are further analyzed, and the LS-DYNA software is used to investigate rigid–flexible coupling dynamics. The elastic deformation of the wing membrane, kinematic characteristics of the linkage mechanism, and modes of the whole system are calculated. Static analysis of the structure reveals that the foldable wing has excellent stiffness characteristics and load-bearing capacity. The bionic foldable wing is constructed using three-dimensional (3D) printing technology, and its folding and unfolding performance is tested. Evaluation of its performance shows that the bionic wing has a large fold ratio and can achieve stable folding and unfolding motions. A slightly tighter assembly between the pin and the hinge hole ensures that the wing does not fold back during flapping.
Large Eddy Simulation of Film Cooling Over a Flat Plate in Supersonic Flow
Authors: Sharma Hitesh , Singh Dushyant , Singh Ashutosh Kumar
Published: December 2020

In the present work, large eddy simulation (LES) was performed to access the film cooling performance in the supersonic flow over a flat plate with a perpendicular slot injection configuration. The study was carried out for three mainstream Mach No.; Mα = 1.2, 2.67, and 3.3 and three coolant stream Mach No.: 0.05, 0.1, and 0.15. In supersonic flow, temperature rise inside the boundary layer is a major issue considering it causes high rates of heat transfer to the coolant film. To select a suitable LES sub-grid scale (SGS) model, LES results obtained from the present study using the LES SGS models such as Smagorinky-Lilly, wall adapted local eddy viscosity (WALE), and wall-modeled LES (WMLES) models were compared with DNS results of Keller and Kloker. The parametric study showed that the higher mainstream Mach No. caused increased wall temperature and reduced effectiveness. The film cooling effectiveness appeared to reduce almost by 10% when the mainstream Mach No. is increased from 1.2 to 2.67; however, no apparent difference was observed in effectiveness between the mainstream Mach No. 2.67 and 3.3. It was found that doubling and tripling the coolant stream Mach No. from 0.05 to 0.1 and 0.15, the length of potential core region also doubled and tripled, respectively, from 4 X/S to 8 X/S and 13 X/S and hence significant improvement in the film cooling effectiveness was observed.
Prediction of NOx Emissions for a Range of Engine Hardware Configurations Using Artificial Neural Networks
Authors: Papaioannou Nick , Fang XiaoHang , Leach Felix , Davy Martin H.
Published: December 2020

The predictive ability of artificial neural networks where a large number of experimental data are available, has been studied extensively. Studies have shown that ANN models are capable of accurately predicting NOx emissions from engines under various operating conditions and different fuel types when trained well. One of the major advantages of an ANN model is its ability to relearn when new experimental data is available, thus continuously improving its accuracy. The present work explored the potential of an ANN model to predict NOx emissions for various engine configurations outside its training envelop. This work also looked into quantifying the amount of new data required to improve the accuracy of the model when exposed to unknown conditions. The chosen ANN model was constructed using data from a high-speed direct injection diesel engine and is capable of accurate NOx emissions over a wide range of operating conditions. The optimized network utilized 14 input parameters and is using 6 neurons in a single hidden layer feed-forward neural network. Experimental data from the various engine configurations tested, were then used to predict NOx from the existing ANN model. The results indicate that when the new data are within the baseline training envelop, the ANN model is capable of accurate NOx prediction even when there are substantial changes in engine configuration such as piston material. Similar results were also observed when the injector nozzle is changed. However, the model’s performance drops significantly when new data, outside the baseline training envelop, were employed indicating that additional training is required. As such, various methods for retraining the ANN model were explored with the selected method showing the best compromise between new-data accuracy and old-data accuracy retention. The retrained ANN model developed was found to be an effective tool in predicting NOx emissions for different engine configurations and operating conditions.
Computational Fluid Dynamics Investigation on Multiple Injector Concepts at Different Swirl Ratios in a Heavy Duty Engine
Authors: Nyrenstedt Gustav , Ben Houidi Moez , Babayev Rafig , Im Hong , Johansson Bengt
Published: December 2020

Numerical studies investigated how multiple injectors can reduce the high heat losses associated with swirl, as a further attempt to enhance thermal efficiencies of high-pressure combustion engines. Computational fluid dynamics simulations employed the Reynolds-averaged Navier-Stokes approach for one, two- and three injector configurations. High and medium load conditions were simulated at different swirl ratios. In general, an increased swirl ratio reduced engine efficiency. However, for all swirl ratios, three injectors provided higher efficiency. Two injectors decreased the heat losses for all swirl ratios, and injection against the swirl with multiple injectors provided high efficiencies. In combination with a waste heat recovery system, the two-injector case delivered an efficiency increase of 2.2%-points for the medium load case. Three injectors delivered high efficiencies at all swirl ratios as an effect of a high flow rate and low heat losses. The multiple injector configurations evaluated in this study proved non-beneficial for the high load case. Spray-to-spray interactions lowered the combustion — and indicated efficiencies. However, the three injector case showed potential for delivering high indicated efficiency, from an increased flow rate, at high loads.
Multi-Dimensional Modeling of the CFR Engine for the Investigation of SI Natural Gas Combustion and Controlled End-Gas Autoignition
Authors: Bestel Diego , Bayliff Scott , Marchese Anthony , Olsen Daniel , Windom Bret , Xu Hui
Published: December 2020

Engine knock and misfire are barriers to pathways leading to high-efficiency Spark-Ignited (SI) Natural Gas engines. The general tendency to knock is highly dependent on engine operating conditions and the fuel reactivity. The problem is further complicated by low emission limits and the wide range of chemical reactivity in pipeline quality natural gas. Depending on the region and the source of the natural gas, its reactivity, described by its methane number (analogous to the octane number for liquid SI fuels) can span from 65–95. In order to realize diesel-like efficiencies, SI natural gas engines must be designed to operate at high BMEP near knock limits over a wide range of fuel reactivity. This requires a deep understanding regarding the combustion-engine interactions pertaining to flame propagation and end-gas autoignition (EGAI). However, EGAI, if controlled, provides an opportunity to increase SI natural gas engine efficiency by increasing combustion rate and the total burned fuel, mitigating the effects of the slow flame speeds of natural gas fuels which generally reduce BMEP and increase unburned hydrocarbon emissions. For this reason, in order to study EGAI phenomenon, the present work highlights multi-dimensional computational fluid dynamics (CFD) models of the Cooperative Fuel Research (CFR) engine. The CFR engine models are used to investigate fuel-engine interactions that lead to EGAI with natural gas, including effects of fuel reactivity, engine operating parameters, and exhaust gas recirculation (EGR). A Three-Pressure Analysis, performed with GT-Power, was used to estimate initial and boundary conditions for the three-dimensional CFD model. CONVERGE CFD v2.4 was used for the three-dimensional CFD modeling where the level set G-Equation model and SAGE detailed chemical kinetics solver were used. An assessment of the different modeling approaches is also provided to evaluate their limitations, advantages and disadvantages, and for which situations they are most applicable. Model validation was performed with experimental data taken with a CFR engine over varying compression ratio, CA50, EGR fraction, and IMEP and shows good agreement in Peak Cylinder Pressure (PCP), PCP crank angle, and the location of the 10%, 50%, and 90% mass fraction burned (CA10, CA50, and CA90, respectively). The models can predict the onset crank angle and pressure rise rate for light, medium, and heavy EGAI under a variety of fuel reactivities and engine operating conditions.
Cavitation-Suppressing Orifice Design Applied to a Heavy-Duty Diesel Engine Injector Operating With Gasoline
Authors: Torelli Roberto , Pei Yuanjiang , Zhang Yu , Traver Michael , Som Sibendu
Published: December 2020

Measurements of fuel injectors via non-destructive X-ray techniques can provide unique insights about an injector’s internal surface. Using real measured geometry rather than nominal design geometry in computational fluid dynamics simulations can improve the accuracy of the numerical models dramatically. Recent work from the authors investigated the influence of the injector design on the internal flow development and occurrence of cavitation in a production multi-hole heavy-duty diesel injector operating with a straight-run gasoline for gasoline compression ignition (GCI) applications. This was achieved by evaluating a series of design parameters which showed that the intensity and duration of cavitation structures could be mitigated by acting on certain injector parameters such as K-factor, orifice inlet ellipticity, and sac-to-orifice radius of curvature. In the present work, the findings from the previous parametric study were combined to generate two attempts at improving the injector design and numerically evaluate their ability to suppress cavitation inside the orifices at three levels of injection pressure (1000, 1500, and 2500 bar), while operating with the same high-volatility gasoline fuel. Qualitative and quantitative analyses showed that, compared to the results obtained with the original X-ray scanned geometry, the improved designs were able to prevent fuel vapor formation at the two lowest injection pressures and avoid super-cavitation at the higher pressure. It was shown that these results were due to the strong influence that the orifice shape can have on the pressure and fuel vapor volume fraction distributions within the orifices. The informed design choices proposed in this study can therefore be vital for extending the durability and reliability of heavy-duty injectors for GCI applications.
Numerical Investigation of Pre-Chamber Jet Combustion in a Light-Duty Gasoline Engine
Authors: Zhang Anqi , Yu Xin , Engineer Nayan , Zhang Yu , Pei Yuanjiang
Published: December 2020

Open-cycle engine simulations of a passive pre-chamber operating inside a direct-injected gasoline engine are performed and analyzed in this study. A comprehensive three-dimensional computational fluid dynamics (CFD) model has been formulated with state-of-the-art physical sub-models to account for the complex processes of engine gas exchange, fuel injection and mixing, ignition, and combustion. Numerical results are validated against experimental measurements under low load condition with high internal EGR. Realistic modeling considerations are discussed to ensure proper fidelity. In particular, the mixture conditions and flow motions could present very different features between the pre- and main chamber, which requires comprehensive simulation of the full engine cycle and imposes challenges for combustion modeling. Practically validated chemical kinetics models are essential for proper prediction of cylinder pressure history of pre-chamber jet combustion systems. Detailed analysis is then carried out to highlight key processes associated with pre-chamber operation, including residual scavenging, fuel/air mixture formation, flow pattern and turbulence development within the pre-chamber, and the ignition of main chamber mixture by issued turbulent jets. Numerical evaluation of pre-chamber design variants has been attempted, and less commonly investigated geometry parameters such as swirl nozzles and nozzle umbrella angle are found impactful for pre-chamber ignition performances.
Meta-modeling for urban noise mapping
Authors: Lesieur Antoine , Aumond Pierre , Mallet Vivien , Can Arnaud
Published: December 2020

Urban noise mapping generally consists of simulating the emission and attenuation of noise in an area by following rules such as common noise assessment methods. The computational cost makes these models unsuitable for applications such as uncertainty quantification, where thousands of simulations may be required. One solution is to replace the model with a meta-model that reproduces the expected noise levels with highly reduced computational costs. The strategy is to generate the meta-model in three steps. The first step is to generate a training sample exploring the large dimension model's inputs set. The second step is to reduce the dimension of the outputs. In the third step, statistical interpolators are defined between the projected values of the training sample over the reduced space of the outputs. Radial basis functions or kriging are used as interpolators. The meta-model was built using the open source software NoiseModelling. This study compares the proximity of the meta-model outputs to the model outputs against the reduced basis, the class of the kriging covariance function, and the training sample size. Simulations using the meta-model are more than 10 000 times faster than the model while maintaining the main behavior.
Planar acoustic scattering by a multi-layered split ring resonator
Authors: Montiel Fabien , Chung Hyuck
Published: December 2020

The problem of two-dimensional acoustic scattering of time-harmonic plane waves by a multi-ringed cylindrical resonator is considered. The resonator is made up of an arbitrary number of concentric sound-hard split rings with zero thickness. Each ring opening is oriented in any direction. The acoustics pressure field in each layered region enclosed between adjacent rings is described by an eigenfunction expansion in polar coordinates. An integral equation/Galerkin method is used to relate the unknown coefficients of the expansions between adjacent regions separated by a ring. The multiple scattering problem is then formulated as a reflection/transmission problem between the layers, which is solved using an efficient iterative scheme. An exploration of the parameter space is conducted to determine first, the conditions under which the lowest resonant frequency can be minimised, and second, how non-trivial resonances of the multi-ring resonators can be explained from those of simpler arrangements, such as a single-ring resonator. It is found here that increasing the number of rings while alternating the orientation lowers the first resonant frequency, and exhibits a dense and nearly regular resonant structure that is analogous to the rainbow trapping effect.
Deimmunized Lysostaphin Synergizes with Small-Molecule Chemotherapies and Resensitizes Methicillin-Resistant
Staphylococcus aureus
to β-Lactam Antibiotics
Authors: Fang Yongliang , Kirsch Jack R. , Li Liang , Brooks Seth A. , Heim Spencer , Tan Cynthia , Eszterhas Susan , Cheng Hao D. , Zhao Hongliang , Xiong Yan Q. , Griswold Karl E.
Published: December 2020

There is an urgent need for novel agents to treat drug-resistant bacterial infections, such as multidrug-resistant
Staphylococcus aureus
(MRSA). Desirable properties for new antibiotics include high potency, narrow species selectivity, low propensity to elicit new resistance phenotypes, and synergy with standard-of-care (SOC) chemotherapies.
The Polyaminoisoprenyl Potentiator NV716 Revives Old Disused Antibiotics against Intracellular Forms of Infection by Pseudomonas aeruginosa
Authors: Wang Gang , Brunel Jean-Michel , Bolla Jean-Michel , Van Bambeke Françoise
Published: December 2020

Active efflux confers intrinsic resistance to multiple antibiotics in
Pseudomonas aeruginosa
, including old disused molecules. Beside resistance, intracellular survival is another reason for failure to eradicate bacteria with antibiotics.
Type I Natural Killer T Cells as Key Regulators of the Immune Response to Infectious Diseases
Authors: Gálvez Nicolás M. S. , Bohmwald Karen , Pacheco Gaspar A. , Andrade Catalina A. , Carreño Leandro J. , Kalergis Alexis M.
Published: December 2020

The immune system must work in an orchestrated way to achieve an optimal response upon detection of antigens. The cells comprising the immune response are traditionally divided into two major subsets, innate and adaptive, with particular characteristics for each type. Type I natural killer T (iNKT) cells are defined as innate-like T cells sharing features with both traditional adaptive and innate cells, such as the expression of an invariant T cell receptor (TCR) and several NK receptors. The invariant TCR in iNKT cells interacts with CD1d, a major histocompatibility complex class I (MHC-I)-like molecule.
Iron Flocs and the Three Domains: Microbial Interactions in Freshwater Iron Mats
Authors: Brooks Chequita N. , Field Erin K.
Published: December 2020

Freshwater iron mats are dynamic geochemical environments with broad ecological diversity, primarily formed by the iron-oxidizing bacteria. The community features functional groups involved in biogeochemical cycles for iron, sulfur, carbon, and nitrogen.
The Protein Kinase A-Dependent Phosphoproteome of the Human Pathogen Aspergillus fumigatus Reveals Diverse Virulence-Associated Kinase Targets
Authors: Shwab E. Keats , Juvvadi Praveen R. , Waitt Greg , Shaheen Shareef , Allen John , Soderblom Erik J. , Bobay Benjamin G. , Asfaw Yohannes G. , Moseley M. Arthur , Steinbach William J.
Published: December 2020

PKA is essential for the virulence of eukaryotic human pathogens. Understanding PKA signaling mechanisms is therefore fundamental to deciphering pathogenesis and developing novel therapies.
A Noncanonical DNA Damage Checkpoint Response in a Major Fungal Pathogen
Authors: Shor Erika , Garcia-Rubio Rocio , DeGregorio Lucius , Perlin David S.
Published: December 2020

In order to preserve genome integrity, all cells must mount appropriate responses to DNA damage, including slowing down or arresting the cell cycle to give the cells time to repair the damage and changing gene expression, for example to induce genes involved in DNA repair. The Rad53 protein kinase is a conserved central mediator of these responses in eukaryotic cells, and its extensive phosphorylation upon DNA damage is necessary for its activation and subsequent activity.
Why Are Some Listeria monocytogenes Genotypes More Likely To Cause Invasive (Brain, Placental) Infection?
Authors: Vázquez-Boland José A. , Wagner Martin , Scortti Mariela
Published: December 2020

Although all isolates of the foodborne pathogen
Listeria monocytogenes
are considered to be pathogenic, epidemiological evidence indicates that certain serovar 4b lineages are more likely to cause severe invasive (neuromeningeal, maternal-fetal) listeriosis. Recently described as
L. monocytogenes
“hypervirulent” clones, no distinctive bacterial trait has been identified so far that could account for the differential pathogenicity of these strains.
Recombinant ACE2 Expression Is Required for SARS-CoV-2 To Infect Primary Human Endothelial Cells and Induce Inflammatory and Procoagulative Responses
Authors: Nascimento Conde Jonas , Schutt William R. , Gorbunova Elena E. , Mackow Erich R.
Published: December 2020

SARS-CoV-2 infects pulmonary epithelial cells through ACE2 receptors and causes ARDS. COVID-19 causes progressive respiratory failure resulting from diffuse alveolar damage and systemic coagulopathy, thrombosis, and capillary inflammation that tie alveolar responses to EC dysfunction.
Salmonella
versus the Microbiome
Authors: Rogers Andrew W. L. , Tsolis Renée M. , Bäumler Andreas J.
Published: December 2020

A balanced gut microbiota contributes to health, but the mechanisms maintaining homeostasis remain elusive. Microbiota assembly during infancy is governed by competition between species and by environmental factors, termed habitat filters, that determine the range of successful traits within the microbial community.
Short-Chain Fatty Acid-Producing Gut Microbiota Is Decreased in Parkinson’s Disease but Not in Rapid-Eye-Movement Sleep Behavior Disorder
Authors: Nishiwaki Hiroshi , Hamaguchi Tomonari , Ito Mikako , Ishida Tomohiro , Maeda Tetsuya , Kashihara Kenichi , Tsuboi Yoshio , Ueyama Jun , Shimamura Teppei , Mori Hiroshi , Kurokawa Ken , Katsuno Masahisa , Hirayama Masaaki , Ohno Kinji
Published: December 2020

Twenty studies on gut microbiota in PD have been reported, whereas only one study has been reported on iRBD from Germany. iRBD has the highest likelihood ratio to develop PD. Our meta-analysis of iRBD in Japan and Germany revealed increased mucin-layer-degrading genus
Akkermansia
in iRBD.
Discovery of Euryhaline Phycoerythrobilin-Containing
Synechococcus
and Its Mechanisms for Adaptation to Estuarine Environments
Authors: Xia Xiaomin , Lee Puiyin , Cheung Shunyan , Lu Yanhong , Liu Hongbin
Published: December 2020

Understanding the strategies developed by different microbial groups to adapt to specific niches is critical. Through genome and transcriptome analyses of two newly isolated novel euryhaline
Synechococcus
strains, this study revealed that cluster 5 phycoerythrobilin-containing
Synechococcus
, which are thought to be strictly marine strains, could be abundant in low-salinity waters of the Pearl River estuary (salinity <15 ppt) and explained the molecular mechanisms that enabled them to adapt the low and fluctuating salinity in the estuarine environment.
Supplemental Material: Hikurangi Plateau subduction a trigger for Vitiaz arc splitting and Havre Trough opening (southwestern Pacific)
Authors: Hoernle Kaj , al. et
Published: December 2020

Supplemental information about the samples and analytical methods, including Fig. S1), Table S1 (geochemical data), and Table S2 (replicates and reference materials).
Supplemental Material: Protracted northward drifting of South China during the assembly of Gondwana: Constraints from the spatial-temporal provenance comparison of Neoproterozoic–Cambrian strata
Authors: Chen Qiong , Zhao Guochun , al. et
Published: December 2020

Table S1: In-situ U-Pb ages and Hf isotopic data of detrital zircons from the Neoproterozoic–Cambrian samples from the western and eastern margins of South China.
Kayexalate-induced colitis and rectal stricture
Authors: Krishnamurthy Padmini , Agrawal Sangeeta
Published: December 2020

A 57-year-old man underwent emergency laparoscopic loop colostomy for acute recto-sigmoid obstruction. He was hospitalised 2 months previously, at another facility for diabetic ketoacidosis (DKA) and hyperkalaemia. He had no gastrointestinal symptoms prior to the hospitalisation. Both surgical exploration and intraoperative sigmoidoscopy showed ulcerations of sigmoid colon and proximal rectum with a pinhole stricture in mid-rectum. After ruling out all aetiologies, and due to persistence of the colonic ulcerations on a follow-up colonoscopy, a diagnosis of Crohn’s colitis was made, and the patient was started on infliximab and 6-mercaptopurine (6-MP). Six months later, on rereview of all the biopsies, it was noted that a key element of presence of crystals suggestive of Kayexalate on the initial colorectal biopsies was missed. It was later found out that the patient had received rectal Kayexalate for treatment of DKA at the other facility. Hence, infliximab and 6-MP were both discontinued. All the colonoscopies, following the discontinuation of the medications, showed complete resolution of colitis but persistence of the mid-rectum stricture. This was treated with a fully covered metal stent for 12 weeks with only partial improvement of the stricture. He was hence referred for ultra-low anterior resection of rectum and take down of colostomy.
Total control introducer-aided nasotracheal intubation using a videolaryngoscope in an anticipated difficult airway: a novel technique
Authors: Kumar Abhishek , Gupta Nishkarsh , Kumar Vinod , Bhargava Tanvi
Published: December 2020

Nasotracheal intubation can be challenging due to undesirable incidence of nasal bleeding and soft tissue injuries. The bleeding can obscure glottis visualisation, increase the total intubation time, the risk of aspiration and oxygen desaturation. Total control introducer is a new airway adjunct with a flexible shaft, articulating tip and an intuitive depth control system, which can be used in difficult airway scenarios to improve the success of nasal intubations.
Yersinia pseudotuberculosisinfection with severe localised inflammation and ulceration of the ileum in a heart transplant patient
Authors: Heuvelmans Maarten , Lammertink Marieke H A , Kusters Johannes G , Bruns Anke H W , Monkelbaan Jan F
Published: December 2020

In this case, we present an uncommon gastrointestinal infection in an immunocompromised patient that was solely diagnosed because of close collaboration between treating physicians and microbiologists. The patient is a 42-year-old male who underwent heart transplantation 5 years earlier. He presented with fever, weight loss, diarrhoea and tiredness. Initial investigations could not elucidate the aetiology of his symptoms. The patient was referred to the department of infectious diseases for further evaluation. Serology forYersiniaspecies was ordered and the result was suggestive for the possibility of aYersiniaspecies infection. Close collaboration between treating physicians and microbiologists followed and led to additional investigations, which revealed the diagnosis of aYersinia pseudotuberculosisinfection with extensive lesions in the gastrointestinal tract. Treatment with ciprofloxacin resulted in complete resolution of symptoms and healing of the gastrointestinal lesions. In conclusion, this case underlines the need for a multidisciplinary approach to complex patients of which symptoms have yet to be understood.
Cerebral contrast staining mimicking parenchymal haemorrhage in a stroke patient
Authors: Lim Elvin Yuan Ting , Swaminathan Saravana Kumar
Published: December 2020

A 75-year-old female patient presented with signs and symptoms of a right hemispheric syndrome. A CT scan of the brain with angiogram showed an acute infarct in the right middle cerebral artery (MCA) territory secondary to thromb-occlusion of the M1 segment of the right MCA. A follow-up CT scan 2 weeks later showed a large hyperdense region in the infarcted area. With the aid of a dual-energy CT scan, this was eventually shown to be due to contrast staining from an earlier administration of iodinated contrast on the same day, rather than frank haemorrhagic conversion of the recent right MCA infarct.
Radiation-induced sarcoma presenting as a gluteal abscess: a diagnostic and therapeutic challenge
Authors: Mahalingam Sudharshan , Sundaramurthi Sudharsanan , Krishnaraj Balamourougan , Sistla Sarath Chandra
Published: December 2020

Sarcomas are a rare and fatal treatment complication following radiotherapy. Radiation-induced sarcomas (RISs) presenting as a gluteal abscess is a rarity, accounting for its varied presentation. We present a case of a middle-aged woman, post-chemo-radiation for carcinoma cervix 5 years ago, who presented with gluteal abscess. Achieving haemostasis post incision and drainage under anaesthesia was a challenge. On further evaluation, she was diagnosed with radiation-induced gluteal soft tissue sarcoma. Haemostasis was achieved after radiation following failed attempts of surgical and radiological interventions. She is currently planned for chemotherapy. Cancer survivors have an increased risk of developing a second malignancy following radiation treatment. RISs are highly aggressive, exhibit a varied clinical presentation and pose a challenge in early diagnosis; thus, have a poor outcome. RISs pose a diagnostic challenge; any dubious lesion in the previously irradiated field should raise suspicion and prompt aggressive management.
Iris melanocytoma and secondary glaucoma
Authors: Xavier Catarina , Hipolito-Fernandes Diogo , Cardigos Joana , Magriço Ana
Published: December 2020

Iris melanocytoma (IM) is a rare variant of iris nevus with distinctive clinical and histopathological features. A 66-year-old woman, with a history of right eye pigmented iris nevus, presented to us with a recent onset of visual acuity decrease in that eye. She had a melanocytic iris lesion with iridocorneal angle invasion, peripheral corneal adhesion, pupil corectopia, sectorial cataract and high intraocular pressure. Ultrasound biomicroscopy did not exclude malignant transformation, so excisional biopsy was performed revealing the presence of IM without signs of atypia. Subsequently, the patient underwent cataract surgery combined with iridoplasty and later anab externotrabeculectomy. Most cases of IM remain stable and require no intervention, but in cases of unusual clinical course, with rapid growth or secondary glaucoma, surgical treatment is indicated as a diagnostic and therapeutic measure. This case report highlights the importance of a timely and multidisciplinary ophthalmological approach for a better visual outcome.
Unexpected borderline ovarian tumours (BOT) in late pregnancy: challenges in management and review of literature
Authors: Ande Elizabeth , Jain Silky , Rouabhi Schahrazed , Yoong Wai
Published: December 2020

This case report describes a right-sided borderline ovarian tumour diagnosed unexpectedly following suspected torsion in the third trimester of pregnancy. The patient had had a right mucinous cystadenoma and left serous cystadenoma in her previous pregnancy and underwent bilateral ovarian cystectomy at the time of her first elective caesarean section. The management of borderline ovarian tumours is generally difficult in younger women of reproductive age and is made more complex by pregnancy. The authors share the challenges of managing this condition in pregnancy together with a review of the literature.
A Patient with speechlessness and rhabdomyolysis: a rare presentation of severe hypocalcaemia
Authors: Jiwa Florine Helene , van den Hoek Kim , van Zeijl Clementine Jaantje Joanna , Kooter Albertus Jozef
Published: December 2020

A 29-year-old man with no medical history presented to our emergency department with episodes of sudden speechlessness, hoarseness, vomiting after drinking cold water and spasms of his hands. Chvostek’s and Trousseau’s signs were both seen at presentation. Blood tests revealed severe hypocalcaemia (1.03 mmol/L) and rhabdomyolysis (creatine kinase (CK) of 2962 IU/L). The patient was treated immediately with calcium intravenously with an almost immediate improvement of his voice and quick normalisation of his CK. Additional investigation showed primary hypoparathyroidism in the presence of a vitamin D deficiency, requiring lifelong treatment with calcium supplements and alphacalcidol. Severe hypocalcaemia can be life threatening and prompt treatment is essential. This case reports the unusual first presentation of hypocalcaemia via speechlessness and vomiting together with rhabdomyolysis. Identifying an atypical presentation of hypocalcaemia is critical, for it can be lifesaving.
Factors associated with calendar literacy and last menstrual period (LMP) recall: a prospective programmatic implication to maternal health in Bangladesh
Authors: Sarker Bidhan Krishna , Rahman Musfikur , Rahman Tanjina , Rahman Tawhidur , Rahman Fariya , Khalil Jubaida Jahan , Hasan Mehedi , Mahfuz Sadia Nishat , Ahmmed Faisal , Miah Muhammad Salim , Ahmed Anisuddin , Mitra Dipak , Mridha Malay Kanti , Rahman Anisur
Published: December 2020

Objective

To explore the prevalence and determinants of calendar literacy and last menstrual period (LMP) recall among women in Bangladesh.

Design

Cross-sectional survey.

Settings

Two rural subdistricts and one urban area from three Northern districts of Bangladesh.

Participants

We interviewed 2731 women who had a live birth in the last 1 year.

Primary and secondary outcome measures

The primary outcome variable was LMP recall and the secondary outcome was calendar literacy.

Results

The majority of participants (65%) correctly mentioned the current date according to the English calendar while 12% mentioned according to the Bengali calendar. During the interview sessions, we used three different calendars: Bengali, English and Hijri to assess calendar literacy. We asked women to mark the current date using the calendar on the day of the interview. Almost 61% women marked the English calendar, 16% marked the Bengali calendar and 4% marked the Hijri calendar correctly. Sixty-three per cent women were found as calendar literate who marked any of the calendars. Among the participants, 58% had calendars available at their home and only 10% of women used calendars to track their LMPs. Overall, 53% women were able to recall their recent LMP. Among the calendar literate, 60% could recall their LMPs. Factors found associated with recalling LMP were: completed eight or more years of schooling (adj.OR 1.39), primigravida (adj.OR 1.88), the richest wealth quintile (adj.OR 1.55) and calendar literacy (adj.OR 1.59).

Conclusions

Despite having reasonable calendar literacy and availability, the use of calendars for tracking LMP found very low. Calendar literacy and sociodemographic characteristics were found as the key factors associated with LMP recall. Maternal, neonatal and child health programmes in low-resource settings can promote a simple tool like calendar and target the communities where ultrasound is not available to ensure accurate LMP recall for early pregnancy registration and timely antenatal care coverage.
Psychometric properties and construct validity of PLAYself: a self-reported measure of physical literacy for children and youth
Authors: Jefferies Philip , Bremer Emily , Kozera Tanya , Cairney John , Kriellaars Dean
Published: December 2020

PLAYself is a tool designed for self-description of physical literacy in children and youth. We examined the tool using both the Rasch model and Classical Test Theory to explore its psychometric properties. A random selection of 300 children aged 8–14 years (47.3% female) from a dataset of 8513 Canadian children were involved in the Rasch analysis. The 3 subscales of the measure demonstrated good fit to the Rasch model, satisfying requirements of unidimensionality, having good fit statistics (item and person fit residuals = –0.17–1.47) and internal reliability (Person Separation Index = 0.70–0.82), and a lack of item bias and problematic local dependency. In a separate comparable sample, 297 children also aged 8–14 years (53.9% female) completed the PLAYfun, Physical Self-Description Questionnaire (PSDQ), Physical Activities Measure-Revised (MPAM-R), a physical activity inventory (PLAYinventory), and repeated the PLAYself 7 days later. The tests with this sample confirmed test–retest reliability (intraclass correlation coefficient = 0.81–0.84), and convergent and construct validity consistent with contemporary physical literacy definitions. Overall, the PLAYself demonstrated robust psychometric properties, and is recommended for researchers and practitioners who are interested in assessing self-reported physical literacy.

Novelty: The PLAYself is a self-reported measure of physical literacy This study validates the measure using the Rasch model and classical test theory The PLAYself was found to have strong psychometric properties
Adsorption of 1-chloro-1,2,2,2-tetrafluoroethane on pristine, Al, Ga-doped boron nitride nanotubes: a study involving PBC-DFT, NBO analysis, and QTAIM
Authors: Doust Mohammadi Mohsen , Abdullah Hewa Y.
Published: December 2020

In the present investigation, the feasibility of detecting the 1-chloro-1,2,2,2-tetrafluoroethane gas molecule on the outer surface of pristine single-walled boron nitride nanotube, as well as its aluminium- and gallium-doped structures, was carefully evaluated. For achieving this goal, a periodic boundary condition density functional theory level of study using both HSE06 and B3LYP-D3 functionals together with a 6-311G(d) basis set has been used. Subsequently, the CAM-B3LYP, ωB97XD, and M06-2X functionals with a 6-311G(d) basis set were also employed to consider the single point energies. Natural bond orbital and quantum theory of atoms in molecules were implemented by using the HSE06/6-311G(d) method and the results were compatible with the electronic properties. In this regard, the total density of state, the Wiberg bond index, natural charge, natural electron configuration, donor–acceptor natural bond orbital interactions, and the second-order perturbation energies are performed to explore the nature of the intermolecular interactions. All of the energy calculations and population analyses show that by adsorbing of the gas molecule onto the surface of the considered nanostructures, the intermolecular interactions are of the type of strong chemical adsorption. Between the doped nanotubes, aluminium-doped nanotube has very high adsorption energy compared with gallium. Generally, it was revealed that the sensitivity of the adsorption will be increased when the gas molecule interacts with decorated nanotubes and decrease the HOMO–LUMO band gap; therefore, the change of electronic properties can be used to design suitable nanosensors.