bluuebunny/crossref_metadata_2025 huggingface dataset:
Near-Field Radiative Heat Transfer Between Two α-MoO3 Biaxial Crystals
Authors: Wu Xiaohu , Fu Ceji , Zhang Zhuomin M.
Published: April 2020

The near-field radiative heat transfer (NFRHT) between two semi-infinite α-MoO3 biaxial crystals is investigated numerically based on the fluctuation–dissipation theorem combined with the modified 4 × 4 transfer matrix method in this paper. In the calculations, the near-field radiative heat flux (NFRHF) along each of the crystalline directions of α-MoO3 is obtained by controlling the orientation of the biaxial crystals. The results show that much larger heat flux than that between two semi-infinite hexagonal boron nitride can be achieved in the near-field regime, and the maximum heat flux is along the [001] crystalline direction. The mechanisms for the large radiative heat flux are explained as due to existence of hyperbolic phonon polaritons (HPPs) inside α-MoO3 and excitation of hyperbolic surface phonon polaritons (HSPhPs) at the vacuum/α-MoO3 interfaces. The effect of relative rotation between the emitter and the receiver on the heat flux is also investigated. It is found that the heat flux varies significantly with the relative rotation angle. The modulation contrast can be as large as two when the heat flux is along the [010] direction. We attribute the large modulation contrast mainly to the misalignment of HSPhPs and HPPs between the emitter and the receiver. Hence, the results obtained in this work may provide a promising way for manipulating near-field radiative heat transfer between anisotropic materials.
Effects of Heat Flux, Mass Flux, Inlet Fluid Subcooling, and Channel Orientation on Subcooled Flow Boiling in a High-Aspect-Ratio Rectangular Microchannel
Authors: Li Wei , Chen Zengchao , Li Junye , Zhou Kan , Feng Zhaozan
Published: April 2020

An experimental investigation of subcooled flow boiling in a high-aspect-ratio, one-sided heating, silicon-based rectangular microchannel was conducted utilizing de-ionized water as the working fluid. The microchannel was 5.01 mm wide and 0.52 mm high, having a hydraulic diameter of 0.94 mm and an aspect ratio (AR) of 10. The heat flux, mass flux, and inlet fluid subcooling were in the ranges of 0–30 W/cm2, 200–500 kg/m2 s, and 5–20 °C, respectively, while the orientations were vertical and horizontal. Parametric study on heat transfer characteristics including the onset of nucleate boiling (ONB), heat transfer coefficient (HTC), and critical heat flux (CHF) was carried out combined with flow visualization. Significant appearance of ONB without boiling hysteresis was observed in the boiling curve, accompanied with bubble nucleation. Nucleate boiling occurred first near the exit, where the HTC increased more sharply, while easier bubble nucleation was found near the sides. Unique time-dependent flow pattern consisting of isolated bubbly flow, elongated bubbly flow, partial dry-out, and rewetting process was observed. More nucleation sites were activated at higher heat flux, while higher initial heat flux and wall superheat for ONB as well as higher CHF value were obtained at higher mass flux and inlet subcooling. Compared to the vertical channel, higher wall temperature and pressure drop with larger oscillation amplitudes were found for the horizontal counterpart, where the merged bubbles agglomerated in the heating section, resulting in earlier dry-out which deteriorated heat transfer.
Forming Diverse Teams From Sequentially Arriving People
Authors: Ahmed Faez , Dickerson John , Fuge Mark
Published: April 2020

Collaborative work often benefits from having teams or organizations with heterogeneous members. In this paper, we present a method to form such diverse teams from people arriving sequentially over time. We define a monotone submodular objective function that combines the diversity and quality of a team and proposes an algorithm to maximize the objective while satisfying multiple constraints. This allows us to balance both how diverse the team is and how well it can perform the task at hand. Using crowd experiments, we show that, in practice, the algorithm leads to large gains in team diversity. Using simulations, we show how to quantify the additional cost of forming diverse teams and how to address the problem of simultaneously maximizing diversity for several attributes (e.g., country of origin and gender). Our method has applications in collaborative work ranging from team formation, the assignment of workers to teams in crowdsourcing, and reviewer allocation to journal papers arriving sequentially. Our code is publicly accessible for further research.
Mobility Analysis of Thin-Panel Origamis Based on a Coplanar 2-Twist Screw System
Authors: Wang Sen , Huang Hailin , Li Bing , Yang Xiaojun
Published: April 2020

This paper presents an intuitive approach for mobility analysis of thin-panel origamis based on a coplanar 2-twist screw system, which consists of a pair of parallel/concurrent line vectors. In this study, we first proved that in any thin-panel origami, the allowable instantaneous mobility for any two facets connected to a third one can be described by a coplanar 2-twist screw system because this mobility is generated by two coplanar creases in the third facet. Second, the mobility of the basic origami units with a single facet loop was analyzed by using this coplanar 2-twist screw system. Third, the mobility analysis approach was extended to analyze the mobility of other planar/circular arraying origami patterns with multiple facet loops; typical origami patterns such as leaf-fold, Miura-ori were subjected to this analysis process. Furthermore, we proved that the proposed approach can be applied to the mobility analysis of complicated origamis; this approach proved to be considerably more intuitive than the traditional approach for mobility analysis.
Effects of Jet Dilution and Co-Flow on Sooting Characteristics of Hydrocarbon Fuels
Authors: Goh S. F. , Kusadomi S. , Gollahalli S. R.
Published: April 2020

A study was conducted to understand the effects of dilution and co-flow on the sooting characteristics of hydrocarbon fuels. Measurements of the critical mass flow rate of a fuel at the threshold of smoking and the mass flow rate of the dilution gas (nitrogen) required to suppress smoking at several fuel flow rates were obtained. At the same time, the radiation emission and flame heights were also measured. Also recorded was the axial radiation profile at the critical fuel mass flow rate. Three fuels of differing sooting propensities were used: ethylene (C2H4), propylene (C3H6), and propane (C3H8). A 3.2 mm ID burner was employed. The results showed that propylene had the highest critical fuel flow rate and the highest nitrogen dilution required to suppress smoking, followed by ethylene and propane. Besides, propylene produced the highest flame radiation, followed by ethylene and propane. The variation of nitrogen flow rate required for smoke suppression with fuel flow rate exhibited a skewed bell shape for all fuels. The co-flow had no significant effect on flame soot liberation characteristics.
An Analytical Study of Turbulent Dispersion of Bubbles
Authors: Lawson Anthony L. , Parthasarathy Ramkumar N.
Published: April 2020

An analysis of the dispersion of bubbles in homogenous and isotropic turbulent liquid flows was performed to study the effects of bubble and flow characteristics on their dispersion. Bubbles were assumed to be spherical and to follow the fluid motion in the mean. No mass transfer occurred between the bubble and liquid; also, there was no interaction between individual bubbles. It was found that for accurate prediction of bubble dispersion requires a simultaneous consideration of the inertia of the added mass of liquid (because the inertia of the bubble itself is small) and the bubble rise velocity. Normalized bubble diffusivity, root-mean-square fluctuating velocity, and Lagrangian integral time scale were related to two non-dimensional parameters: ratio of the added mass response time to the liquid flow integral time scale, and the ratio of the bubble rise velocity to the root-mean-square liquid velocity fluctuation. In general, the bubble Lagrangian velocity auto-correlations decreased as the rise velocity ratio increased. The dependence of the autocorrelations on the time-scale ratio was complex. A surprising result was that the bubble velocity fluctuations could exceed the liquid velocity fluctuations for certain conditions because of their low inertia.
Prediction of Vibration Properties of Sandwich Panel Using Thick Plate Theory
Authors: Liu Qunli , Zhao Yi
Published: April 2020

The vibration of a sandwich panel with two identical isotropic facesheets and an orthotropic core was studied. The governing partial differential equation was derived using variational principle. Kirchhoff’s theory was applied to describe the deformation of the panel, and the rotational effect was taken into consideration. The frequencies of free vibration of a rectangular panel can be predicted based on the proposed analytical model. Results based on the proposed model were compared with those from thin plate theory. The effect of orthotropic core on frequencies was also discussed.
Applications of Materials Selection for Joining Composite/Alloy Piping Systems
Authors: Crosby Karen E. , Smith Brett H. , Mensah Patrick F. , Stubblefield Michael A.
Published: April 2020

A study in collaboration between investigators at Southern University and Louisiana State University in Baton Rouge, Louisiana and NASA/MSFC is examining materials for modeling and analysis of heat-activated thermal coupling for joining composite to composite/alloy structures. The short-term objectives of this research are to develop a method for joining composite or alloy structures, as well as to study the effects of thermal stress on composite-to-alloy joints. This investigation will result in the selection of a suitable metallic alloy. Al-Li alloys have potential for this purpose in aerospace applications due to their excellent strength-to-weight ratio. The study of Al-Li and other alloys is of significant importance to this and other aerospace as well as offshore related interests. Further research will incorporate the use of computer aided design and rapid prototype hardware for conceptual design and verification of a potential composite piping delivery system.
Analysis of Adhesion Bond: Rehablitation of Deficient Structures Using Composite Plates
Authors: Hailu Haftay , Woldesenbet Eyassu
Published: April 2020

The state of considerable number of structurally deficient or functionally obsolete infrastructure in the US, along with the prohibitive cost of replacement has opened a way for the search of innovative methods of rehabilitation. One such method is the use of composite plates adhesively bonded to concrete to prevent the propagation of crack within the concrete structure. Due to their high specific strength and corrosion resistance, composite materials serve better than conventional construction materials. The load transfer and the resulting stress distribution in the composite plate and adhesive layer can be investigated analytically and numerically. In this paper, analytical model is selected and used to analyze and predict the failure conditions of the adhesive. Parametric study is also included to understand the effects of the length and thickness of the adhesion bond, the modulus of the adherents and the adhesive. Finally, a general equation of the adhesion bond strength of the single-lap joint is presented for general shear stress-strain behavior of the adhesive.
New Technologies for Managing Oil Field Waste
Authors: Veil John A.
Published: April 2020

Each year, the oil industry generates millions of barrels of wastes that need to be properly managed. For many years, most oil field wastes were disposed of at a significant cost. However, over the past decade, the industry has developed many processes and technologies to minimize the generation of wastes and to more safely and economically dispose of the waste that is generated. Many companies follow a three-tiered waste management approach. First, companies try to minimize waste generation when possible. Next, they try to find ways to reuse or recycle the wastes that are generated. Finally, the wastes that cannot be reused or recycled must be disposed of.

For the past seven years, Argonne National Laboratory has been evaluating the feasibility of various oil field waste management technologies for the U.S. Department of Energy. This paper provides brief overviews of four of the technologies Argonne has reviewed. In the area of waste minimization, the industry has developed synthetic-based drilling muds (SBMs) that have the desired drilling properties of oil-based muds without the accompanying adverse environmental impacts. Use of SBMs avoids significant air pollution from work boats hauling offshore cuttings to shore for disposal. Downhole oil/water separators have been developed to separate produced water from oil at the bottom of wells. The produced water is directly injected to an underground formation without ever being lifted to the surface, thereby avoiding potential for groundwater or soil contamination. In the area of reuse/recycle, Argonne has worked with Southeastern Louisiana University and industry to develop a process to use treated drill cuttings to restore wetlands in coastal Louisiana. Finally, Argonne has conducted a series of four baseline studies to characterize the use of salt cavern for safe and economic disposal of oil field wastes.
Experimental Investigation of Multiple Solutions for Liquid Holdup in Upward Inclined Stratified Flow
Authors: Smith Steven P. , Gregory Garry A. , Yarranton Harvey W.
Published: April 2020

The mechanistic model of Taitel and Dukler [1] has previously been reported to exhibit a region in which three solutions exist for the height of the gas-liquid interface in the stratified/wave flow regime. Most laboratory studies have not dealt with flow rates in the ranges where the multiple solutions occur. An experimental study has been carried out at the University of Calgary to obtain such data.

The object of this work is to review the relevant theory, investigate situations where theory suggests that multiple solutions should exist, and attempt to show whether or not such solutions do physically exist.
Computation of Turbulent Gas-Particle Flows Behind a Bluffbody
Authors: Chen X.-Q. , Renksizbulut M. , Li X.
Published: April 2020

A numerical analysis of multisized glass particles interacting with a confined bluffbody flow was performed by combining the finite-volume method for the gaseous flow with the Lagrangian approach for the particulate flow. The second-moment Reynolds-stress model was used to predict the turbulent gaseous flow in a gas-particle system, where an improved eddy-interaction model was used to predict turbulence-induced particle dispersion. The interaction between the two phases was accounted for in terms of coupling sources. Numerical predictions of two-phase mean and fluctuating velocities for different particle sizes were compared with corresponding experimental data. Reasonably good agreement was achieved for the mean properties of both the gaseous and particulate flows.
RWAG: A Tool for Dynamic Web Application Development
Authors: Song Hongqing , Huang Stephen
Published: April 2020

The purpose of this tool, Rapid Web Application Generator (RWAG), is to allow a user to create a database-driven web application without the knowledge of DBMS and server-side programming. RWAG automatically generates database definitions and ASP pages for manipulating the data. The advantages of using RWAG are as follows: first, a user can create web applications in minutes without ever having to write any code (no need to know ASP, Perl, or Java); secondly, an advanced user can leverage his knowledge of ASP, Perl, Java, JavaScript, HTML, XML and DBMS to expand and customize the web application; thirdly, RWAG allows a user to own a record in the database, which means a record can only be edited by the user who creates it; finally, RWAG provides multiple user access levels. RWAG is ideal for a group of users to share information on the web.
Developing a Proactive Environmental Management System (PEMS) in Offshore West Africa
Authors: Ogunsanya B. O. , Ifebajo A. J.
Published: April 2020

Every industry that seeks to remain efficient and relevant in this millennium should constantly be looking for ways of becoming more environmentally responsible — no business may call itself efficient if it threatens the environment within which it operates. As the quest for hydrocarbons intensifies in our deeper waters, we see environmental performance quality playing an increasingly critical role in every company’s business performance.

In the last couple of years, reports from onshore E&P activities in Nigeria have shown that operating in the Niger Delta region poses some of the toughest challenges in the world. This region has witnessed a spate of attacks on oil and gas facilities, staff and contractors. Consequently, major oil and gas players have to contend with complex operational uncertainties due to increased pressures from the local communities for improved environmental control measures.

In this project, we have outlined safe and effective plans, actions, and procedures to help pre-empt these pressures; maintain harmony with local communities, and effectively manage operational uncertainties within complex environmental settings like the Nigerian Niger Delta area. A proactive environmental management style based on continuous consultation, goal-oriented monitoring, as well as a continuous improvement attitude (CIA) are some of the various solutions proposed in this work.

Finally, we are confident that this kind of environmental management system will undoubtedly enhance the economic viability, as well as the global competitiveness of our deep-water fields in offshore West Africa.
Multiphase Flow Wax Deposition Modeling
Authors: Matzain Ahmadbazlee , Apte Mandar S. , Zhang Hong-Quan , Volk Michael , Redus Clifford L. , Brill James P. , Creek Jeff L.
Published: April 2020

Results are presented from two-phase flow wax deposition tests using a state-of-the-art, high pressure, multiphase flow test facility. Wax deposition was found to be flow pattern dependent and occurs only along the pipe wall in contact with the waxy crude oil. The deposition buildup trend at low mixture velocities is similar to that observed in laminar single-phase flow tests. The buildup trend at high mixture velocities is similar to that observed in turbulent single-phase flow tests. Thinner and harder deposits at the bottom than at the top of the pipe were observed in horizontal intermittent flow tests. Thicker and harder deposits were observed at low liquid superficial velocity than at high liquid superficial velocity annular flow tests. No wax deposition was observed along the upper portion of the pipe in stratified flow tests.

A semi-empirical kinetic model tailored for the wax deposition tests predicted wax thickness with an acceptable accuracy, especially at high oil superficial velocity. Deposition rate reduction due to shear stripping and rate enhancement due to entrapment of oil and other mechanisms not accounted for by the classical Fick’s mass diffusion theory were incorporated through the use of dimensionless variables and empirical constants derived from the wax deposition data. The kinetic model, although semi-empirical, provides an insight for future model development.
Real-Time Multiphase Metering Using Non-Intrusive Microwave Sensor
Authors: Hogan B. , Al-Shamma’a A. I. , Lucas J.
Published: April 2020

At the University of Liverpool we have developed a real-time, non-intrusive multiphase dielectric meter capable of measuring the dielectric properties of different mixtures of oil, gas and water in full well stream flow. The design of such a microwave cavity using a range of rf and microwave is described. The experimental results with a wide range of multiphase mixtures from 0 to 100% are reported. In this paper we also present the implementation of a neural network to simulate the response of the meter under all conceivable conditions. Other parameters including pump speed, temperature, salt and sand are also discussed.
Global Optimization of Gas Allocation to a Group of Wells in Artificial Lift Using MATLAB
Authors: Alarcón Gabriel A. , Torres-Monzón Carlos F. , Gonzalo Nellyana , Gómez Luis E.
Published: April 2020

Continuous flow gas lift is one of the most common artificial lift method in the oil industry and is widely used in the world. A continuous volume of gas is injected at high pressure into the bottom of the tubing, to gasify the oil column and thus facilitate the extraction. If there is no restriction in the amount of injection gas available, sufficient gas can be injected into each oil well to reach maximum production. However, the injection gas available is generally insufficient. An inefficient gas allocation in a field with limited gas supply also reduces the revenues, since excessive gas injection is expensive due to the high gas prices and compressing costs. Therefore, it is necessary to assign the injection gas into each well in optimal form to obtain the field maximum oil production rate. The gas allocation optimization can be considered as a maximization of a nonlinear function, which models the total oil production rate for a group of wells. The variables or unknowns for this function are the gas injection rates for each well, which are subject to physical restrictions. In this work a MATLAB™ nonlinear optimization technique with constraints was implemented to find the optimal gas injection rates. A new mathematical fit to the “Gas-Lift Performance Curve” is presented and the numeric results of the optimization are given and compared with results of other methods published in the specialized literature. The optimization technique proved fast convergence and broad application.
Numerical Computations of Higher Class Solutions for 2D Polymer Flows Using PTT Constitutive Model
Authors: Surana K. S. , Nayak H. Vijayendra
Published: April 2020

This paper presents formulations, computations and investigations of the solutions of classes C00 and C11 for two dimensional viscoelastic fluid flows in u, v, p, τijp, τijs with Phan-Thien-Tanner (PTT) constitutive model using p-version least squares finite element formulation (LSFEF). The main thrust of the research work presented in the paper is to employ ‘right classes of interpolations’ and the ‘best computational strategy’ 1) to obtain numerical solutions of governing differential equations (GDEs) for increasing Deborah numbers 2) investigate the nature of the computed solutions with the aim of establishing limiting values of the flow parameters beyond which the solutions may be possible to compute, but may not be meaningful.

The investigations presented in this paper reveal the following: a) The manner in which the stresses are non-dimensionalized significantly influences the performance of the iterative procedure of solving non-linear algebraic equations. b) Solutions of the class C00 are always the wrong class of solutions of GDEs in variables u, v, p, τijp and τijs and thus spurious. c) C11 class of solutions are the right class of solutions of the GDEs in variables u, v, p, τijp and τijs. d) In the flow domains, containing sharp gradients of the dependent variables, conservation of mass is difficult to achieve at lower p-levels (worse for coarse meshes). e) An augmented form of GDEs are proposed that always ensure conservation of mass at all p-levels regardless of the mesh and the nature of the solution gradients. f) Stick-slip problem is used as a model problem. We demonstrate that converged solutions are possible to compute for all flow rates reported and that the detailed examination of the solution characteristics reveals them to be in agreement with all the physics of the flow, g) Numerical studies with graded meshes and high p-levels presented in this paper are aimed towards establishing and demonstrating detail behavior of local as well as global nature of the computed solutions, h) Various norms are proposed and tested to judge local and global dominance of elasticity or viscous behavior i) New definitions are proposed for elongational (extensional) viscosity. The proposed definitions are more in conformity and agreement with the flow physics compared to currently used definitions j) A significant aspect and strength of our work is that we utilize straightforward p-version LSFEF with C00 and C11 type interpolations without linearizing GDEs and that SUPG, SUPG/DC, SUPG/DC/LS operators are neither needed nor used.
Computations of Solutions of Higher Classes of Gasdynamics Equations in Lagrangian Frame of Reference Using a New Theoretical and Computational Framework
Authors: Surana K. S. , Ahmadi Ali R.
Published: April 2020

In this paper we present and utilize a new theoretical and computational framework for computing solutions of higher classes of one dimensional transient Navier-Stokes partial differential equations in Lagrangian frame of reference using ρ, u, T variables. The approach utilizes ‘strong form’ of the governing differential equations (GDEs) and least squares method in constructing integral form. The currently used finite element approaches seek convergence of a solution in a fixed order space by h, p, or hp-adaptive processes. The fundamental point of departure in the proposed approach is that we seek the convergence of the computed converged solution over the spaces of different orders containing the basis functions. With this approach, dramatically higher convergence rates than those obtained for h, or hp-processes are achievable and the sequence of progressively converged solutions over the spaces of progressively increasing order in fact converge to the strong solution (analytical or theoretical) of the partial differential equation. It is demonstrated using one-dimensional transient Navier-Stokes equations for compressible fluid flow in Lagrangian frame of reference in ρ, u, T that in the presence of physical diffusion and dissipation, our computed converged solutions have exactly the same characteristics as the strong solutions. Compression of air in a rigid cylinder is used as the model problem.
Separation in Flat Indentation of Orthotropic Laminated Beams
Authors: Chen Chun-Fu
Published: April 2020

Problems of indentation of orthotropic laminated beams due to flat punches arc solved. Exact solution methods for a subsidiary problem are developed first for both the simply-supported and clamped-ended cases. A numerical iteration algorithm is then employed to assess the possible separation and the real contact area and the contact stresses for a given punch width and a beam span. The contact stresses and separation results for the beams of a typical span reveal various contact conditions that depend only upon the punch width but not the magnitude of the applied load. For a symmetric lamination of the beam, a wide range of punch widths and beam spans are implemented to detect the critical punch widths rendering the onset of separation between the punch and the beam and to establish the threshold curve for the critical aspect ratio of the beam versus the relative punch width. The effects of both the end support condition and slacking sequence of the beam upon the contact and separation scenarios as well as the threshold behavior are thoroughly evaluated.
Analysis of the Charge Movements in Barrel Finishing
Authors: Boschetto A. , Marchetti E. , Veniali F.
Published: April 2020

A laboratory scale barrel has been designed and constructed in order to achieve information about the charge movements in tumbling operation. The charge has been evidenced to be moving for almost the whole time with the same speed than the barrel. The velocity gradients are thus present mainly in the active layer of the charge and depend upon the rotational speed of the barrel. Also the relative speed of the work-piece with respect to the charge depends on the rotational speed.
An Experimental Study of Controlled Gas-Phase Combustion in Porous Media for Enhanced Recovery of Oil and Gas
Authors: Sanmiguel Javier E. , Mehta S. A. (Raj) , Moore R. Gordon
Published: April 2020

Gas-phase combustion in porous media has many potential applications in the oil and gas industry. Some of these applications are associated with: air injection based improved oil recovery (IOR) processes, formation heat treatment for remediation of near well-bore formation damage, downhole steam generation for heavy oil recovery, in situ preheating of bitumen for improved pumping, increased temperatures in gas condensate reservoirs, and improved gas production from hydrate reservoirs. The available literature on gas-phase flame propagation in porous media is limited to applications at atmospheric pressure and ambient temperature, where the main application is in designing burners for combustion of gaseous fuels having low calorific value. The effect of pressure on gas-phase combustion in porous media is not well understood.

Accordingly, this paper will describe an experimental study aimed at establishing fundamental information on the various processes and relevant controlling mechanisms associated with gas-phase combustion in porous media, especially at elevated pressures. A novel apparatus has been designed, constructed and commissioned in order to evaluate the effects of controlling parameters such as operating pressure, gas flow rate, type and size of porous media, and equivalence ratio on combustion characteristics. The results of this study, concerned with lean mixtures of natural gas and air and operational pressures from atmospheric (88.5 kPa or 12.8 psia) to 433.0 kPa (62.8 psia), will be presented. It will be shown that the velocity of the combustion front decreases as the operating pressure of the system increases, and during some test operating conditions, the apparent burning velocities are over 40 times higher than the open flame laminar burning velocities.
Introduction to molecular dynamics simulations
Authors: Vollmayr-Lee Katharina
Published: April 2020

We provide an introduction to molecular dynamics simulations in the context of the Kob–Andersen model of a glass. We introduce a complete set of tools for doing and analyzing the results of simulations at fixed NVE and NVT. The modular format of the paper allows readers to select sections that meet their needs. We start with an introduction to molecular dynamics independent of the programming language, followed by introductions to an implementation using python and then the freely available open source software package lammps. We also describe analysis tools for the quick testing of the program during its development and compute the radial distribution function and the mean square displacement using both python and lammps.
The Hamilton–Jacobi equation: An alternative approach
Authors: Houchmandzadeh Bahram
Published: April 2020

The Hamilton–Jacobi equation (HJE) is one of the most elegant approaches to Lagrangian systems such as geometrical optics and classical mechanics, establishing the duality between trajectories and waves and paving the way naturally for quantum mechanics. Usually, this formalism is taught at the end of a course on analytical mechanics through its technical aspects and its relation to canonical transformations. I propose that the teaching of this subject be centered on this duality along the lines proposed here, and the canonical transformations be taught only after some familiarity with the HJE has been gained by the students.
2020 Oersted Medal Presentation: If opportunity doesn't knock, build a door—My path to active dissemination of active learning
Authors: Sokoloff David R.
Published: April 2020

I've had the good fortune to be able to influence the way physics is taught around the world. The influence of a number of very special colleagues, the synergy of events, and a bit of chutzpah have all contributed. I will comment on these factors and also describe what I believe are the essential features of active dissemination of research-validated active learning strategies.
Cardiorespiratory Fitness Predicts Higher Inhibitory Control in Patients With Substance Use Disorder
Authors: Tavares Vagner D.O. , da Costa Kell G. , Cabral Daniel A.R. , Rego Maria L.M. , Price Menna , Fontes Eduardo B.
Published: April 2020

Impaired inhibitory control has been shown in individuals with substance use disorder (SUD). Cardiorespiratory fitness has been described as a potential factor to improve inhibitory control; however, the benefits in individuals with SUD are unclear. The aim of this study was to investigate the relationship between cardiorespiratory fitness with general and drug-specific inhibitory control in individuals with SUD. Sixty-two male participants under treatment for SUD performed a general and drug-specific inhibitory control test (go/no-go) and a cardiorespiratory fitness test. Cardiorespiratory fitness, age, and years of drug use were inversely associated with reaction time for both general and drug-specific inhibitory control. In addition, the regression models showed that cardiorespiratory fitness predicts general and drug-specific inhibitory control adjusted for age and time of drug use. However, cardiorespiratory fitness predicts equally both general and drug-specific inhibitory control. These findings suggest that increasing cardiorespiratory fitness could provide benefits in the inhibitory function of individuals with SUD.
Undoing Gender or Overdoing Gender? Women MMA Athletes’ Intimate Partnering and the Relational Maintenance of Femininity
Authors: Hamilton Justen
Published: April 2020

Recent scholarship suggests that women in martial arts and combat sports have increasingly begun to undo gender by challenging gender norms and constructing new femininities. Most of this research, however, has focused on gender dynamics within martial arts and combat sports settings, rather than outside of them. For this study, I conducted semistructured interviews with 40 professional women’s mixed martial arts athletes to examine the extent to which these women challenged gender norms in their intimate relationships. My data revealed that because they possess traits that are traditionally interpreted as masculine, many of the heterosexual women in my sample actually oversubscribe to gender norms in their intimate relationships to combat feelings of feminine insecurity. I argue, therefore, that rather than undoing gender, these women overdo gender in their intimate relationships. This study provides a cautionary tale to the celebrations of undoing gender for women combat sports athletes.
Pooled Multicenter Analysis of Cardiovascular Safety and Population Pharmacokinetic Properties of Piperaquine in African Patients with Uncomplicated Falciparum Malaria
Authors: Wattanakul Thanaporn , Ogutu Bernhards , Kabanywanyi Abdunoor M. , Asante Kwaku-Poku , Oduro Abraham , Adjei Alex , Sie Ali , Sevene Esperanca , Macete Eusebio , Compaore Guillaume , Valea Innocent , Osei Isaac , Winterberg Markus , Gyapong Margaret , Adjuik Martin , Abdulla Salim , Owusu-Agyei Seth , White Nicholas J. , Day Nicholas P. J. , Tinto Halidou , Baiden Rita , Binka Fred , Tarning Joel
Published: April 2020

Dihydroartemisinin-piperaquine has shown excellent efficacy and tolerability in malaria treatment. However, concerns have been raised of potentially harmful cardiotoxic effects associated with piperaquine. The population pharmacokinetics and cardiac effects of piperaquine were evaluated in 1,000 patients, mostly children enrolled in a multicenter trial from 10 sites in Africa. A linear relationship described the QTc-prolonging effect of piperaquine, estimating a 5.90-ms mean QTc prolongation per 100-ng/ml increase in piperaquine concentration.
Oligomerization of the Vesicular Stomatitis Virus Phosphoprotein Is Dispensable for mRNA Synthesis but Facilitates RNA Replication
Authors: Bloyet Louis-Marie , Morin Benjamin , Brusic Vesna , Gardner Erica , Ross Robin A. , Vadakkan Tegy , Kirchhausen Tomas , Whelan Sean P. J.
Published: April 2020

All NNS RNA viruses, including the human pathogens rabies, measles, respiratory syncytial virus, Nipah, and Ebola, possess an essential L-protein cofactor, required to access the N-RNA template and coordinate the various enzymatic activities of L. The polymerase cofactors share a similar modular organization of a soluble N-binding domain and a template-binding domain separated by a central oligomerization domain. Using a prototype of NNS RNA virus gene expression, vesicular stomatitis virus (VSV), we determined the importance of P oligomerization. We find that oligomerization of VSV P is not required for any step of viral mRNA synthesis but is required for efficient RNA replication. We present evidence that this likely occurs through the stage of loading soluble N onto the nascent RNA strand as it exits the polymerase during RNA replication. Interfering with the oligomerization of P may represent a general strategy to interfere with NNS RNA virus replication.
Phylogeography and Antigenic Diversity of Low-Pathogenic Avian Influenza H13 and H16 Viruses
Authors: Verhagen Josanne H. , Poen Marjolein , Stallknecht David E. , van der Vliet Stefan , Lexmond Pascal , Sreevatsan Srinand , Poulson Rebecca L. , Fouchier Ron A. M. , Lebarbenchon Camille
Published: April 2020

Wild birds play a major role in the epidemiology of low-pathogenic avian influenza viruses (LPAIVs), which are occasionally transmitted—directly or indirectly—from them to other species, including domestic animals, wild mammals, and humans, where they can cause subclinical to fatal disease. Despite a multitude of genetic studies, the antigenic variation of LPAIVs in wild birds is poorly understood. Here, we investigated the evolutionary history, intercontinental gene flow, and antigenic variation among H13 and H16 LPAIVs. The circulation of subtypes H13 and H16 seems to be maintained by a narrower host range, in particular gulls, than the majority of LPAIV subtypes and may therefore serve as a model for evolution and epidemiology of H1 to H12 LPAIVs in wild birds. The findings suggest that H13 and H16 LPAIVs circulate independently of each other and emphasize the need to investigate within-clade antigenic variation of LPAIVs in wild birds.
Nanobody-Mediated Neutralization Reveals an Achilles Heel for Norovirus
Authors: Koromyslova Anna D. , Devant Jessica M. , Kilic Turgay , Sabin Charles D. , Malak Virginie , Hansman Grant S.
Published: April 2020

This research discovered and analyzed two different types of MNV-neutralizing nanobodies. The top-binding nanobodies sterically inhibited the receptor-binding site, whereas the dimeric-binding nanobodies interfered with a structural modification associated with cofactor binding. Moreover, we found that the capsid contained a number of vulnerable regions that were essential for viral replication. In fact, the capsid appeared to be organized in a state of flux, which could be important for cofactor/receptor-binding functions. Blocking these capsid-binding events with nanobodies directly inhibited essential capsid functions. Moreover, a number of MNV-specific nanobody binding epitopes were comparable to human norovirus-specific nanobody inhibitors. Therefore, this additional structural and inhibition information could be further exploited in the development of human norovirus antivirals.
Persistence of Varicella-Zoster Virus-Specific Plasma Cells in Adult Human Bone Marrow following Childhood Vaccination
Authors: Eberhardt Christiane S. , Wieland Andreas , Nasti Tahseen H. , Grifoni Alba , Wilson Elizabeth , Schmid D. Scott , Pulendran Bali , Sette Alessandro , Waller Edmund K. , Rouphael Nadine , Ahmed Rafi
Published: April 2020

Childhood varicella-zoster virus (VZV) immunization induces immune memory responses that protect against primary VZV infection, chicken pox. In the United States, routine childhood VZV vaccination was introduced only 2 decades ago. Hence, there is limited information on the longevity of B and CD4 T cell memory, which are both important for protection. Here, we showed in 15 healthy young adults that VZV-specific B and CD4 T cell responses are detectable in bone marrow (BM) and blood up to 20 years after vaccination. Specifically, we measured antibody-secreting plasma cells in the BM and VZV-specific CD4 T cells in BM and blood. These findings suggest that childhood VZV vaccination induces long-lived immunity.
Carbonate platform production during the Cretaceous
Authors: Pohl Alexandre , Donnadieu Yannick , Godderis Yves , Lanteaume Cyprien , Hairabian Alex , Frau Camille , Michel Julien , Laugie Marie , Reijmer John J.G. , Scotese Christopher R. , Borgomano Jean
Published: April 2020

Platform carbonates are among the most voluminous of Cretaceous deposits. The production of carbonate platforms fluctuated through time. Yet, the reasons for these fluctuations are not well understood, and the underlying mechanisms remain largely unconstrained. Here we document the long-term trend in Cretaceous carbonate platform preservation based on a new data compilation and use a climate-carbon cycle model to explore the drivers of carbonate platform production during the Cretaceous. We show that neritic carbonate preservation rates followed a unimodal pattern during the Cretaceous and reached maximum values during the mid-Cretaceous (Albian, 110 Ma). Coupled climate-carbon cycle modeling reveals that this maximum in carbonate deposition results from a unique combination of high volcanic degassing rates and widespread shallow-marine environments that served as a substrate for neritic carbonate deposition. Our experiments demonstrate that the unimodal pattern in neritic carbonate accumulation agrees well with most of the volcanic degassing scenarios for the Cretaceous. Our results suggest that the first-order temporal evolution of neritic carbonate production during the Cretaceous reflects changes in continental configuration and volcanic degassing. Geodynamics, by modulating accommodation space, and turnovers in the dominant biota probably played a role as well, but it is not necessary to account for the latter processes to explain the first-order trend in Cretaceous neritic carbonate accumulation in our simulations.
Facial trauma aggravating paediatric orbital cellulitis
Authors: Laycock Juliet , Wright Oliver James , Geyton Thomas , Bowles Philippe
Published: April 2020

We describe a case of paediatric orbital cellulitis with subperiosteal abscess following blunt facial trauma. Clinical features of orbital cellulitis developed on day 1 post-trauma. A subperiosteal collection subsequently formed lateral to the globe, causing significant ocular compromise. Surgical drainage and sinus washout were performed via external incisions, with satisfactory outcome. This case highlights how trauma may represent a non-sinogenic aggravating factor in orbital cellulitis. We describe how a subperiosteal abscess may vary depending on its aetiology, and how the surgical approach can be modified to locate and drain a laterally sited subperiosteal abscess.
Effect of long-term rigid gas-permeable contact lens wear on keratoconus progression
Authors: Araki Satoko , Koh Shizuka , Kabata Daijiro , Inoue Ryota , Morii Daichi , Maeda Naoyuki , Shintani Ayumi , Jhanji Vishal , Nishida Kohji
Published: April 2020

Background/aims

To investigate the chronological corneal changes associated with long-term rigid gas-permeable contact lens (RGP-CL) wear in patients with keratoconus (KC).

Methods

Clinical records of 405 patients with KC or with KC suspect were retrospectively reviewed. Patients with mild-to-moderate KC and uneventful follow-up were classified into the CL (RGP-CL wear) and non-CL (without CL wear) groups. Inclusion criteria were (1) at least 3-year follow-up and (2) Scheimpflug-based corneal imaging examination at each visit. The anterior (ARC) and posterior (PRC) radius of curvature obtained in a 3.0 mm optical zone, the thinnest pachymetry reading of the corneal thickness (Tmin), and maximum keratometry values (Kmax) were investigated as tomographic parameters.

Results

Twenty-two and 15 patients who met the inclusion criteria were included in the CL and non-CL groups, respectively (31 and 20 eyes, respectively). The mean observation periods were 75 (CL group) and 63 (non-CL group) months. A multivariable non-linear regression analysis to assess the change in tomographic parameters over the follow-up period and difference of the trend between the two groups demonstrated no significant differences in the chronological change in ARC, PRC and Tmin between the CL and non-CL groups (p=0.318, p=0.280 and p=0.874, respectively).

Conclusion

Based on corneal tomographic evaluation over 5–6 years, the effects of long-term RGP-CL wear had no effect on KC progression.
Conceptual model for pluralistic healthcare behaviour: results from a qualitative study in southwestern Uganda
Authors: Sundararajan Radhika , Mwanga-Amumpaire Juliet , King Rachel , Ware Norma C
Published: April 2020

Introduction

Medical pluralism, or concurrent utilisation of multiple therapeutic modalities, is common in various international contexts, and has been characterised as a factor contributing to poor health outcomes in low-resource settings. Traditional healers are ubiquitous providers in most regions, including the study site of southwestern Uganda. Where both informal and formal healthcare services are both available, patients do not engage with both options equally. It is not well understood why patients choose to engage with one healthcare modality over the other. The goal of this study was to explain therapeutic itineraries and create a conceptual framework of pluralistic health behaviour.

Methods

In-depth interviews were conducted from September 2017 to February 2018 with patients seeking care at traditional healers (n=30) and at an outpatient medicine clinic (n=30) in Mbarara, Uganda; the study is nested within a longitudinal project examining HIV testing engagement among traditional healer-using communities. Inclusion criteria included age ≥18 years, and ability to provide informed consent. Participants were recruited from practices representing the range of healer specialties. Following an inductive approach, interview transcripts were reviewed and coded to identify conceptual categories explaining healthcare utilisation.

Results

We identified three broad categories relevant to healthcare utilisation: (1) traditional healers treat patients with ‘care’; (2) biomedicine uses ‘modern’ technologies and (3) peer ‘testimony’ influences healthcare engagement. These categories describe variables at thehealthcare provider,healthcare systemandpeerlevels that interrelate to motivate individual engagement in pluralistic health resources.

Conclusions

Patients perceive clear advantages and disadvantages to biomedical and traditional care in medically pluralistic settings. We identified factors at the healthcare provider, healthcare system and peer levels which influence patients’ therapeutic itineraries. Our findings provide a basis to improve health outcomes in medically pluralistic settings, and underscore the importance of recognising traditional healers as important stakeholders in community health.