bluuebunny/crossref_metadata_2025 huggingface dataset:
Review of Chemical EOR Projects in Venezuela: From Light to Extra-Heavy Oil Reservoirs
Authors: Rodriguez M. Fernancelys
Published: October 2021

Venezuela is widely recognized as an oil producer country of great potential thanks to its huge hydrocarbon resources located in Eastern Venezuela and Maracaibo basins, comprising the largest oil reserves in the world, with around 302 billion barrels according to recent OPEC and EIA estimates [1].

Despite those immense hydrocarbon resources, oil production in Venezuela is a challenge in mature and waterflooded reservoirs, as well as in thin highly viscous oil reservoirs where thermal IOR/EOR methods are not technically and/or economically feasible. This is the case of many oil fields in Lake Maracaibo and in La Faja Petrolifera Del Orinoco (La FPO), where the application of Chemical Enhanced Oil Recovery (CEOR) methods is being envisaged with a view to increasing oil recovery factors.

The objective of this article is to review most of the Venezuelan CEOR projects reported in the literature to identify the main insights/status of each reported project and its potentiality of application to increase oil recovery. A detailed description of each project and its main conclusions is given.

According to this literature review, CEOR project evaluations for Venezuelan reservoirs have been performed mostly at laboratory and numerical simulation scales, including several pilot test designs. Only 2 executed pilot tests have been reported (ASP flooding at VLA-6/9/21 Field in Lake Maracaibo and polymer flooding at Petrocedeño Field in La FPO). Despite the encouraging results in terms of oil recovery at laboratory scale, the greatest challenges related to the application of CEOR methods in Venezuelan reservoirs are linked to technical and economic aspects (e.g. high adsorption/retention of chemicals, mobility control, complex emulsions, separation of phases, water treatments, costs of investment, oil prices, etc.).
Nonlinear Roll Damping With Coupling Effect in Regular Beam-Wave
Authors: Asgari Peyman , Fernandes Antonio Carlos
Published: October 2021

Despite of numbers of method to estimate and predict the nonlinear roll damping, it is the mode least understood and the most difficult to determine so far. Reviewing the existing methods reveals that the coupling effects of other modes on roll motion are ignored by assuming just one degree of freedom (1DOF) roll in experiments. The new concept of Most Often Instantaneous Rotation Center - MOIRC proposed by Fernandes and Asgari has brough other parameters, which can help us to improve the roll damping analysis by including the coupling (roll-sway) that results in asymmetric roll responses. This paper, by describing experiments, aims to confirm this roll-sway effect on roll damping coefficient by taking a well posed 3DOF, which allows to follow the instantaneous rotation centers - IRCs. The regular beam-waves experiments were conducted for different frequencies and wave amplitudes. A 3DOF (sway, heave and roll) system identification is used to extract roll damping from the model test. It is shown that the locus of the IRCs follows a straight line and it has a statistical behavior whose probability density function of IRCs with a Cauchy probability density function. For the first time this characteristic is provided experimentally, well matching with the analytical Cauchy distribution.
Wettability Alteration During Low-Salinity Waterflooding in a Deep Tight Carbonate Reservoirs: A Quantitative and Visual Investigation Through Spontaneous Imbibition and Zeta Potentiometric Studies
Authors: Singh N. , Gopani P. H. , Sarma H. K. , Wu F. , Mattey P. S. , Negi D. S. , Srivastava V.
Published: October 2021

This study focusses on the investigation of wettability alteration behavior during low salinity waterflood (LSWF) process in a tight carbonate reservoir through Zeta potential studies in conjunction with spontaneous imbibition tests and estimation of the contact angle between the wetting fluid and the rock surface. This will help in understanding the role rock-oil-brine interactions play during an LSWF process. The classical streaming potential technique were used to determine Zeta potential. Measurements were carried out with diluted brines using different rock samples of in two states: oil-saturated and brine-saturated. The experimental results imply that the value of zeta potential becomes more negative with increasing percentage of dilution (25%, 10%, and 1%). This is attributed to electrical double-layer expansion which is caused, primarily, by the reduced ionic strength. We concluded that rock saturated with oil may give an insight on oil rock interactions while the rock saturated with brine may give insight on rock-brine interactions. The dilution of water helps increase the electrostatic repulsive forces between the two interfaces, which in turns, leads to the incremental recovery during LSWF process. This observation was also confirmed by coreflooding and wettability experiments through spontaneous imbibition tests and contact angle measurements conducted using the same oil-brine-rock systems. This is an investigative study of oil-brine-rock interaction behavior during a LSWF process that is difficult to accomplish through and during a conventional coreflooding displacement test. In addition, this study also couples the relationship between the wettability alteration and oil-brine-rock interactions during an LSWF process.
Research on Calculation Method of Density and Rheology of High-Temperature High-Pressure Drilling Fluid
Authors: Wang Lei , Yang Jin , Li Zhengkang , He Xinyue , Li Lei , Zhou Xu
Published: October 2021

With the strengthening of exploration and development of deep strata and offshore oil and gas resources, more and more deep wells and deep-water wells have put forward higher requirements for drilling fluid performance. The high-temperature high-pressure of deep well and the low temperature environment of deep well have important influence on the rheology and density of drilling fluid. A new method for calculating the rheology and density of high -temperature high-pressure (HTHP) drilling fluid is proposed and studied in this paper. In this paper, the HTHP rheological data are used to predict the shear stress under different shear rates, and then the wellbore rheological parameters are predicted and analyzed. For the calculation of drilling fluid density, the classical component method static density calculation model established by Hoberock model based on drilling fluid components is analyzed and improved in this paper. The obtained model predicts that the maximum absolute error of drilling fluid density under different temperature and pressure is 0.02 g/cm3, and the absolute error is controlled within 2 %.
Numerical Assessment of Turbulence Effects on Water Entry of a Hemisphere
Authors: Wang Shan , Guedes Soares C.
Published: October 2021

Water entry of a rigid hemisphere is simulated using the unsteady incompressible Reynolds-Average Navier-Stokes (RANS) equations and volume of fluid (VOF) method, which are implemented in the open-source library OpenFoam. The solver InterDyMFoam is applied and the algorithm PIMPLE which is a combination of PISO (Pressure Implicit with Splitting of Operators) and SIMPLE (Semi-Implicit Method for pressure-Linked Equations) algorithms are used in the simulations. A second-order backward difference scheme is applied for the temporal discretization. A convergence and uncertainty study is performed considering different resolutions and constant Courant number (CFL) using the procedures recommended by ITTC. The comparisons of slamming loads and motions between the CFD simulations are presented using both laminar and turbulence fluid models for the hemisphere entering the water at various speeds. Turbulence is modelled with a Reynolds averaged stress (RAS) k-ω two-equation model. The turbulence effects on the slamming loads will be assessed for the case with different entry velocities.
Evaluation of the Negative Stiffness Mechanism on the Performance of a Hinged Wave Energy Converter
Authors: Kamarlouei Mojtaba , Hallak Thiago S. , Gaspar Jose F. , Guedes Soares C.
Published: October 2021

This paper presents the numerical and experimental study of a new spring mechanism adapted to a cone-shaped point absorber wave energy converter (WEC). The WEC is intended to be hinged to a floating wind platform with a long arm to create a combined wind and wave harvesting concept. The main objective of the spring mechanism is to improve the platform restoring moments against the wind thrust forces, generated by the wind turbine while contributing to wave energy harvesting. However, the study is presented for the case where the WEC dynamics is investigated outside the platform and attached to a fixed frame, to validate the mathematical model of the WEC concept. Moreover, the impact on the power harvesting performance is investigated with and without negative springs in this scenario.
Micro-Siting of Floating Turbines Through Multiple-Criteria Decision-Making
Authors: Diaz Hugo , Guedes Soares C.
Published: October 2021

Multi-Criteria Decision Methods (MCDM) as a complement to current practices for identifying an initial compromise solution to the problem of wind turbine micro-siting are proposed. MCDM deals with multiple objectives in decision-making. The main goal of these methods is to choose among several alternatives using decision criteria previously defined. The use of MCDM guarantees the identification of the alternative that better performs than all the others according to the selected criteria. After a literature review on available methods for micro-siting of offshore wind turbines in a specific location, and an introduction to the MCDM, the usefulness and potential of MCDM in siting floating wind turbines is highlighted. The MCDM methods can add new parameters to the floating wind farms’ layout process. The results of this study support the potential role of these methods as crucial tools to technology developers and decision-makers.
Ultimate Strength Behavior of Cracked Ship Panels: a Review
Authors: Attia Ashraf , El-Kilani Heba S. , Saad-Eldeen S.
Published: October 2021

Cracks of various sizes and orientations may arise at many locations under conditions of pitting corrosion, local stress concentration, fatigue and impact loads. It is essential to evaluate the effect of cracks on the ultimate strength and collapse behaviors of various ship structural members, so as to avoid complete structural failure. The assessment of this effect would serve the life-cycle management, maintenance and repair strategies aiming to ensure structural longevity of ships and offshore steel structures. A review of the advances carried out during the last few years, shows that the effect of locked and propagated cracks on the ultimate strength behavior is complex since it cannot be isolated from the effect of initial imperfections and corrosion. Published experimental attempts were a good base, but most literature is based on finite element modeling that proved to be a useful tool to generate different possible damage scenarios. Recent empirical formulae had been proposed to estimate the reduction in ultimate strength due to cracks and other factors; some of these formulae may prove to have a practical use to attain a consequence based crack assessment criteria.
Direct CFD Simulation and Experimental Study on Coupled Motion Characteristics of Ship and Tank Sloshing in Waves
Authors: Huang Weigang , He Tao , Yu Jiawei , Wang Qing , Wang Xianzhou
Published: October 2021

It is of great significance to study the tank sloshing, especially the coupling motion between tank sloshing and ship in waves with strong non-linearity and randomness. In this study, the response of the ship with/without tank in regular wave is studied by EFD method and CFD method. All the simulations are carried out by in-house CFD code HUST-Ship (hydrodynamic unsteady simulation technology of ship) to solve RANS equations coupled with six degrees of freedom solid body motion equations. RANS equations are solved by finite difference method and PISO algorithm. A two-equation Shear Stress Transport (SST) k-w turbulence model is used. The simulation results are in good agreement with the experimental results, which also indicates that the result of the tank sloshing simulated by in-house CFD code is reliable. The influence of sloshing on ship motions is estimated by comparing the experimental results between the ship with/without tank in different wave conditions. The coupling motion characteristics between the liquid in the tank and the ship is further studied by the CFD method. The study shows that the influence of tank sloshing on ship motion is different under the action of different regular waves.
Probabilistic Models for Kick Tolerance
Authors: Kristoffersen Martine , Gomes Dalila , Fjelde Kjell Kåre
Published: October 2021

Kick tolerance is an evaluation of how large kick sizes i.e. kick volumes an open hole section can withstand without threatening the formation integrity at the shoe. If a certain kick size cannot be handled safely, the planned open hole section must be shortened, and the casing design must be altered.

Three models for calculating the kick tolerances in a well will be compared for a long and short open hole section for various lengths of bottom hole assembly (BHA). The kick tolerance will be performed probabilistically by use of Monte Carlo simulations where important input parameters are considered as distributions. The paper will focus on where the models differ in their results and discuss various opportunities and challenges with using a probabilistic approach.

The models will be integrated in a Monte Carlo simulation framework where the major input uncertainties will be pore pressure, fracture pressure and initial gas distribution in the well. The output will be a distribution of the casing pressure load that has to be compared to the fracture pressure distribution which results in a certain probability for fracturing for a given kick size. Only gas kick in water-based mud will be considered.

First a transient model based on the single bubble concept was considered and integrated in the Monte Carlo simulation framework. This was first compared against an analytical model which calculates the maximum casing shoe pressure at static shut in conditions. The analytical model considers uncertainty in the initial gas distribution. A transient flow model based on the drift flux model was also considered. Both short and long open hole length were considered. BHA length and kick size were varied.

The results show that the transient flow model provides the least conservative results but also the analytical model reduces the probability for fracturing compared to the single bubble model. In most cases, the maximum casing shoe pressure is achieved when kick is located at the BHA.

This paper extends the application of methods for reliability-based casing design to also include probabilistic kick tolerances. This is a contribution related to how the well design process can become more risk based. Some challenges related to specification of tolerance requirements, required number of Monte Carlo simulations and computing time will be discussed. It also provides an overview of the differences between the models and which parameters that are most important for the results.
Deepwater Steel Catenary Riser System Design for Lingshui 17-2 Project
Authors: He Ning , Yang Hu , Xu Fanli , Cheng Yongming
Published: October 2021

A riser is a key component for transporting produced oil and gas from the subsea wells to the surface production vessel. Through nearly 30 years of design and implementation, Steel Catenary Risers (SCRs) have been found to have the advantages of relatively low cost and good adaptability to floating platform’s motion. This paper investigates deepwater SCR system design for the Lingshui 17-2 (termed LS17-2) project.

This paper first introduces a SCR system for the LS17-2 project. The field for this project is located in the northern South China Sea, with water depth of 1220m to 1560m. LS17-2 consists of a subsea production system, a deep-draft semi-submersible (SEMI), and an export riser/pipeline. The platform was designed to have a large storage capacity with a variable draft during its operation.

Based on deepwater SCR engineering experience, the key SCR design challenges are summarized from the engineering executive perspective. The challenges to the SCR system design for the LS17-2 project include harsh environment condition in South China Sea and the impact on fatigue design for the requirement of 30-years’ service life. They call for design optimization and innovative ideas. The engineering design and analysis are discussed together solutions.

To demonstrate the deepwater SCR system design for LS17-2 project, examples are provided to illustrate the challenges and solutions. The experience learned from this paper should have significant relevance to future SCR design.
Structural Strength Assessment of Dented Steel Tubular Members
Authors: Saad-Eldeen S. , Helal Mahmoud , Fathallah Elsayed
Published: October 2021

Tubular members are widely used in oil and gas offshore production and drilling structures either fixed or mobile units. Due to complex operational conditions, the tubular members are subjected to both age and mechanical related damage, which in turn affect the ability of the structure to withstand the applied loads. This motivates the importance of investigating the behavior of tubular members considering the presence of dentation resulting from collision or falling objects and consequently assessing the residual strength of the damaged members accurately. A series of finite element analysis are performed to study the pre- and post-ultimate strength behavior of intact and locally dented un-stiffened steel tubular members subjected to four-point bending. The effects of dent geometrical parameters; length, width, depth, orientation, and location on the ultimate load carrying capacity are analyzed. The ratio between the diameters to the shell thickness is varied, where combined local and global initial imperfections are considered. Buckling and post collapse analysis as well as modes of failure are studied. Parametric diagrams for the ultimate residual strength as a function of dent geometry and the location of damage are also presented. Several concluding remarks are stated which benefit the structural integrity assessment of tubular steel members.
Efficient Modelling of Harsh Environment Disturbances for DP and Autonomous Ships Simulations
Authors: Zaman Hasanat , Islam Mohammed , Alagili Osama , Khan Mohammad , Imtiaz Syed , Ahmed Salim
Published: October 2021

Numerical modelling of the Arctic ocean dynamics with real-time simulation capability is useful for designing, developing, testing, and validating the performance of Dynamically Positioned (DP) and Autonomous ships/offshore platforms. Advanced simulation technology needs to be developed to predict the expected loads on these systems due to the complex interactions with environmental disturbances. This paper presents models of waves, currents, wind, and ice that comply with the real-time simulation requirements and adequately capture the dynamic characteristics of the most relevant physical processes. A 3D dispersive numerical model is deployed to predict the wave parameters to be utilized to compute the wave loads on a ship with known Response Amplitude Operators (RAO). A uniform current load is then incorporated in a superposition manner by using a combined wave-current field dispersion relation capable of expressing the wavenumber of an interactive wave-current field. The mean and the gust wind components are added to the resultant force components. A multiple regression-based ice model is used to predict the loads caused by an ice field characterized by varied ice thickness, concentration, floe size, drift speed and directions. The stationkeeping performance of a generic DP-controlled ship subjected to environmental disturbances is evaluated for a range of environmental conditions. The proposed models can help design, develop, and evaluate dynamic positioning and autonomous ship controllers’ performance. Another application may be developing a realistic simulation environment to train conventional, DP-controlled and autonomous ship operators.
Integrity Monitoring of Offshore Arctic Pipelines
Authors: Cowin Todd G. , Lanan Glenn A. , Paulin Mike , DeGeer Duane
Published: October 2021

For safe and cost-efficient operations of new and existing offshore Arctic pipelines, monitoring of pipeline structural integrity is imperative. A well-founded pipeline integrity management program can optimize production output, extend the life of the pipeline, and serve as a tool for providing preventative maintenance information. Without the implementation of a routine integrity monitoring campaign, pipeline integrity degradation may go undetected until the point of failure.

Arctic-specific offshore pipeline design and operational challenges, such as strudel scour, seabed ice gouge, pipeline upheaval buckling, permafrost thaw settlement, and remote location increase the risk and severity of a loss of pipeline integrity. These design cases can create abnormal conditions and ground deformations along sections of the pipeline which can be difficult to immediately detect through standard integrity monitoring systems and schedules. Many of the existing offshore pipelines in the Arctic are buried in remote locations under seasonal ice cover and the failure to detect pipeline damage in a timely manner could have severe safety, environmental, and economic consequences. An Arctic pipeline integrity monitoring philosophy can be implemented to provide further mitigation against loss of pipeline structural integrity by means of regular bathymetry surveys, In-Line Inspection (ILI) campaigns and Fiber Optic Cable (FOC) monitoring.

This paper provides a guideline for buried offshore Arctic pipeline integrity monitoring. The guideline covers pipeline integrity assurance incorporated into the pipeline design, the surveys to be completed during installation, as-built assessment of the pipeline profile, the warm-up assessment/implementation needed before start-up, and the integrity inspections to be completed during operations.
Wave Excitation Force Estimation for a Multi-DoF WEC via a Cubature Kalman Filter: Design and Preliminary Results
Authors: Nguyen Hoai-Nam , Tona Paolino , Mérigaud Alexis , Cocho Mathieu , Pichard Alexandre
Published: October 2021

This paper presents the design and implementation of a wave excitation force estimator based on the cubature Kalman filter (CKF) for a CETO 6, a submersed wave energy converter controlled using three power take-off systems attached to the tether lines. Wave excitation force estimation is required by many advanced wav energy converter (WEC) control approaches. However, contrary to the single degree-of-freedom (1-DoF) case, the literature on the design of wave estimators is quite scarce for devices with multiple degrees-of-freedom. The advantages of CKF wave estimator described in the paper are its performance and ease of tuning when working with a high-order system, as it is the case for the 6-DoF linear model used for the design. Preliminary results for all the 6 directions are presented in nominal conditions and also in mismatch conditions, where the estimator is applied to a full nonlinear model of the system, under the action of long-crested and short-crested waves.
On the Plastic Bending Responses of Dented Lined Pipe
Authors: Yuan Lin , Zhou Jiasheng , Liu Haowei , Chen Nian-Zhong
Published: October 2021

Mechanically lined pipe, which was proven to be cost-effective in transporting corrosive hydrocarbons, has been used in many offshore applications. However, one weakness of this product is that the liner is extremely sensitive to geometric imperfections and can wrinkle and collapse under severe loading. As typical damage of the pipeline, the local dent of the lined pipe involves the deformation of both the carrier pipe and the liner, which poses a severe threat to the integrity of the composite structure.

In this paper, we developed a numerical framework to study the responses of the lined pipe during indentation and, more importantly, the influence of local dents on the bending capacity of lined pipes. A slight separation between the liner and the carrier pipe was observed during the indentation, depending on the indenter’s geometric feature. Under bending, the liner typically collapsed earlier than the carrier pipe, causing a considerable reduction of the critical curvature and ultimate load-carrying capacity. The evolution of the deformation of the composite structure during the bending process is presented in this paper. Parametric investigations of some vital variables of the problem were also performed to study their influence on the behavior under indentation and the bending capacity of the composite structure.
A Second Benchmarking Exercise on Estimating Extreme Environmental Conditions: Methodology & Baseline Results
Authors: Mackay Ed , Haselsteiner Andreas F. , Coe Ryan G. , Manuel Lance
Published: October 2021

Estimating extreme environmental conditions remains a key challenge in the design of offshore structures. This paper describes an exercise for benchmarking methods for extreme environmental conditions, which follows on from an initial benchmarking exercise introduced at OMAE 2019. In this second exercise, we address the problem of estimating extreme metocean conditions in a variable and changing climate. The study makes use of several very long datasets from a global climate model, including a 165-year historical run, a 700-year pre-industrial control run, which represents a quasi-steady state climate, and several runs under various future emissions scenarios. The availability of the long datasets allows for an in-depth analysis of the uncertainties in the estimated extreme conditions and an attribution of the relative importance of uncertainties resulting from modelling choices, natural climate variability, and potential future changes to the climate. This paper outlines the methodology for the second collaborative benchmarking exercise as well as presenting baseline results for the selected datasets.
A Model to Assess the Susceptibility of a Multicolumn FOWT Platform to Vortex-Induced Motions in Early Design Stages
Authors: Pesce Celso P. , Amaral Giovanni A. , Mendes Bruno , Oliveira Everton L. , Franzini Guilherme R.
Published: October 2021

As well known, VIM is a complex phenomenon that requires nonlinear models to be constructed and simulated, either through computationally demanding CFD approaches or by making use of reduced-order models (ROM), which are based on phenomenological schemes to emulate the vortex wake dynamics. However, even ROM approaches might be relatively time demanding to be used efficiently during initial stages of design, particularly within optimization schemes. A simple model is herein proposed to treat this rather complex problem in the design context. For a range of current intensities and for a complete turn of current directions, offsets and headings are determined, for which maps of natural periods and corresponding modes of oscillations are constructed. A criterion to inspect modes that are prone to resonance is proposed and polar maps of susceptibility to VIM are plotted. The criterion considers ratios between exciting and natural frequencies. Dominances of translational or yaw motions on resonant modes are quantified and discussed. To assess the proposed strategy, VIM susceptibility polar maps are confronted with results of time domain simulations, using a nonlinear ROM. The OC4-DEEPCWIND Floating Wind Turbine is taken as case-study.
Fast time-domain solution of a nonlinear three-dimensional cochlear model using the fast Fourier transform
Authors: Murakami Yasuki
Published: October 2021

A fast numerical time-domain solution of a nonlinear three-dimensional (3D) cochlear model is proposed. In dynamical systems, a time-domain solution can determine nonlinear responses, and the human faculty of hearing depends on nonlinear behaviors of the microscopically structured organs of the cochlea. Thus, time-domain 3D modeling can help explain hearing. The matrix product, an n2 operation, is a central part of the time-domain solution procedure in cochlear models. To solve the cochlear model faster, the fast Fourier transform (FFT), an n log n operation, is used to replace the matrix product. Numerical simulation results verified the similarity of the matrix product and the FFT under coarse grid settings. Furthermore, applying the FFT reduced the computation time by a factor of up to 100 owing to the computational complexity of the proposed approach being reduced from n2 to n log n. Additionally, the proposed method successfully computed 3D models under moderate and fine grid settings that were unsolvable using the matrix product. The 3D cochlear model exhibited nonlinear responses for pure tones and clicks under various gain distributions in a time-domain simulation. Thus, the FFT-based method provides fast numerical solutions and supports the development of 3D models for cochlear mechanics.
The effective medium for a cylinder with cylindrical inclusions
Authors: Fawcett John A.
Published: October 2021

In this paper, the scattering from a fluid-filled (infinite length) cylinder is considered. This cylinder, C, has a different interior sound speed and density than the surrounding water. Within the cylinder's interior, there are a number of smaller cylinders, inclusions, with yet other sound speeds and densities. The mean coherent field scattered from C is computed using Monte Carlo simulations with respect to the random realizations of the inclusion positions and compared to the results computed using an effective sound speed for C. An original formula for the effective sound speed is derived by equating the reflection coefficient for C (without inclusions) to the expected coherent scattered field from C with inclusions, assuming a single-scattering approximation. A single realization of inclusions is also considered with the backscattered spectra averaged azimuthally over the angle of the source/receiver pair. This result is then compared to the coherent fields predicted by the effective medium theory. This is performed for both spectra and the computed time series.
The Cause of Decreased Pan Evaporation over the Past 50 Years
Authors: Roderick Michael L. , Farquhar Graham D.
Published: October 2021

Changes in the global water cycle can cause major environmental and socioeconomic impacts. As the average global temperature increases, it is generally expected that the air will become drier and that evaporation from terrestrial water bodies will increase. Paradoxically, terrestrial observations over the past 50 years show the reverse. Here, we show that the decrease in evaporation is consistent with what one would expect from the observed large and widespread decreases in sunlight resulting from increasing cloud coverage and aerosol concentration.
Antarctic Radiolaria, Magnetic Reversals, and Climatic Change
Authors: Hays James D. , Opdyke Neil D.
Published: October 2021

The time is now ripe for a concerted attack on the evolutionary, ecological, and molecular aspects of life at high temperatures. Hot springs provide nearly ideal ecosystems for such study, since they are natural environments of great antiquity and relative constancy, where organisms have evolved to meet the environmental challenges of high temperatures. Even from our present limited knowledge, we can draw a number of conclusions.
A battle over the ‘best science’
Authors: Malakoff David
Published: October 2021

In separate moves, Congress sets out to shape how regulators use science, and whose advice they listen to.
The "Alien DNA" of Virulence Genes
Authors: Barinaga Marcia
Published: October 2021

Bacteria do a brisk trade in useful genes, swapping bits of DNA among themselves like baseball cards, and the recently discovered type III secretion genes are clearly foreign to the pathogens now using them. Researchers are still seeking the original source of these “alien” virulence genes.
Plastic Transistors Gain Speed on Silicon
Authors: Service Robert F.
Published: October 2021

First developed in the mid 1980s, organic transistors immediately raised the prospect of using cheap, flexible and lightweight plastic for “smart cards” and other throw-away memory devices, or as the array of switches that control the light emission from each picture element in conventional laptop computer displays. But the devices have never really made it out of the lab because of disappointing processing speeds and because they leaked current when turned off. New research, however, has progressed on both of these fronts and the latest organic transistors virtually match the speed and low-loss characteristics of amorphous silicon devices.
Multilayers and Perovskites Rewrite Rules of Resistance
Authors: Hellemans Alexander
Published: October 2021

10 years ago, Peter Grünberg of the Jülich Research Center in Germany discovered a metallic structure that did not seem to obey the ubiquitous Ohm's law. He constructed a sandwich of two iron layers separated by a thin film of chromium and found that at constant voltage he could vary the current through it simply by applying a magnetic field. The resistance of the structure was no longer a constant. Even greater changes of resistance in magnetic fields were soon found in complex oxides called manganese perovskites, closely related to high-temperature superconductors. These phenomena offer tantalizing prospects for applications such as reading heads in hard disk drives and digital videotape recorders and commercial devices are coming soon.
Slim-Look Superconductors Lead the Applications Race
Authors: Hellemans Alexander
Published: October 2021

A decade on from the discovery of high-temperature superconductivity (HTS), the applications of the these materials expected to hit the market soon are not the high-speed trains and loss-free powerlines originally expected, but electronic devices. So-called bulk applications of HTS hit the buffers because of the materials' poor mechanical properties—they are brittle and crumbly—and their inability to carry large currents. But HTS ceramics have some remarkable electronic properties and it is as thin films that they will first find their way into practical uses, for example as super-sensitive magnetic detectors used for medical diagnosis and very narrow-waveband microwave filters for communications.
Regulatory Small RNA Qrr2 Is Expressed Independently of Sigma Factor-54 and Can Function as the Sole Qrr Small RNA To Control Quorum Sensing in Vibrio parahaemolyticus
Authors: Tague J. G. , Hong J. , Kalburge S. S. , Boyd E. F.
Published: October 2021

The quorum sensing noncoding small RNAs (sRNAs) are present in all
Vibrio
species but vary in number and regulatory roles among species. In the Harveyi clade, all species contain five
qrr
genes, and in
Vibrio harveyi
these are transcribed by sigma-54 and are additive in function.
Structural Basis of Ubiquitin Recognition by a Bacterial Ovarian Tumor Deubiquitinase LotA
Authors: Takekawa Norihiro , Kubori Tomoko , Iwai Tomoya , Nagai Hiroki , Imada Katsumi
Published: October 2021

To successfully colonize, some pathogenic bacteria hijack the host ubiquitin system.
Legionella
OTU-like-DUBs (Lot-DUBs) are novel bacterial deubiquitinases found in effector proteins of
L. pneumophila
. LotA is a member of Lot-DUBs and has two OTU domains (OTU1 and OTU2).
Innovations to maximise impact of a data for decision-making training programme in the Federated States of Micronesia
Authors: Durand A Mark , Hancock W Thane , Cash Haley L , Rouse Ian , Chutaro Emi , Taulung Livinson , Patel Mahomed
Published: October 2021

Accurate and timely health information is an essential foundation for strengthening health systems. Data for decision making (DDM) is a training curriculum designed to enhance capacity of health department staff to capture and use high-quality data to address priority health issues. In 2013, the Pacific Public Health Surveillance Network adapted and piloted the DDM curriculum as an ‘at work, from work, for work’ field epidemiology training programme component for low-income and middle-income Pacific Island jurisdictions. Based on lessons learned from the pilot, we made several innovations, including delivery on-site at each district (rather than bringing trainees to a central location), conducting pre-DDM consultations and ongoing contact with health leaders across the programme, taking more care in selecting trainees and enrolling a larger cohort of students from within each health department. The decentralised programme was delivered in-country at four sites (both at national and state levels) in the Federated States of Micronesia. Following delivery, we performed an external evaluation of the programme to assess student outcomes, benefits to the health department and general programme effectiveness. Of the 48 trainees who completed all four classroom modules, 40 trainees participated in the evaluation. Thirty-two of these trainees completed the programme’s capstone field project. Eighteen of these projects directly contributed to changes in legislation, revised programme budgets, changes in programme strategy to augment outreach and to target disease and risk factor ‘hot spots’.
Sex-specific differences in physical health and health services use among Canadian Veterans: a retrospective cohort study using healthcare administrative data
Authors: St Cyr Kate , Aiken A B , Cramm H , Whitehead M , Kurdyak P , Mahar A L
Published: October 2021

Introduction

Military occupations have historically been, and continue to be, male dominated. As such, female military Veteran populations tend to be understudied, and comparisons of the physical health status and patterns of health services use between male and female Veterans are limited outside of US samples. This study aimed to compare the physical health and health services use between male and female Veterans residing in Ontario, Canada.

Methods

A retrospective cohort of 27 058 male and 4701 female Veterans residing in Ontario whose military service ended between 1990 and 2019 was identified using routinely collected administrative healthcare data. Logistic and Poisson regression models were used to assess sex-specific differences in the prevalence of select physical health conditions and rates of health services use, after multivariable adjustment for age, region of residence, rurality, neighbourhood median income quintile, length of service in years and number of comorbidities.

Results

The risk of rheumatoid arthritis and asthma was higher for female Veterans compared with male Veterans. Female Veterans had a lower risk of myocardial infarction, hypertension and diabetes. No sex-specific differences were noted for chronic obstructive pulmonary disease. Female Veterans were also more likely to access all types of health services than male Veterans. Further, female Veterans accessed primary, specialist and emergency department care at greater rates than male Veterans. No significant differences were found in the sex-specific rates of hospitalisations or home care use.

Conclusions

Female Veterans residing in Ontario, Canada have different chronic health risks and engage in health services use more frequently than their male counterparts. These findings have important healthcare policy and programme planning implications, in order to ensure female Veterans have access to appropriate health services.
Immunosuppression reduction when administering a booster dose of the BNT162b2 mRNA SARS-CoV-2 vaccine in kidney transplant recipients without adequate humoral response following two vaccine doses: protocol for a randomised controlled trial (BECAME study)
Authors: Yahav Dafna , Rozen-Zvi Benaya , Mashraki Tiki , Atamna Alaa , Ben-Zvi Haim , Bar-Haim Erez , Rahamimov R
Published: October 2021

Introduction

Inadequate antibody response to mRNA SARS-CoV-2 vaccination has been described among kidney transplant recipients. Immunosuppression level and specifically, use of antimetabolite in the maintenance immunosuppressive regimen, are associated with inadequate response. In light of the severe consequences of COVID-19 in solid organ transplant recipients, we believe it is justified to examine new vaccination strategies in these patients.

Methods and analysis

BECAME is a single-centre, open-label, investigator-initiated randomised controlled, superiority trial, aiming to compare immunosuppression reduction combined with a third BNT162b2 vaccine dose versus third dose alone. The primary outcome will be seropositivity rate against SARS-CoV-2. A sample size of 154 patients was calculated for the seropositivity endpoint assuming 25% seropositivity in the control group and 50% in the intervention group. A sample of participants per arm will be also tested for T-cell response. We also plan to perform a prospective observational study, evaluating seropositivity among ~350 kidney transplant recipients consenting to receive a third vaccine dose, who are not eligible for the randomised controlled trial.

Ethics and dissemination

The trial is approved by local ethics committee of Rabin Medical Center (RMC-0192-21). All participants will be required to provide written informed consent. Results of this trial will be published; trial data will be available. Protocol amendments will be submitted to the local ethics committee.

Trail registration number

NCT04961229.
Holography and quantum information exchange between systems
Authors: Singh Harvendra
Published: October 2021

In this paper, we estimate the net information exchange between adjacent quantum subsystems holographically living on the boundary of [Formula: see text] space–time. The information exchange is a real-time phenomenon and only after long-time interval it may get saturated. Normally, we prepare systems for small time intervals and measure the information exchange over finite interval only. We find that the information flow between entangled subsystems gets reduced if systems are in excited state whereas the ground state allows maximum information flow at any given time. Especially for [Formula: see text] we exactly show that a rise in the entropy is detrimental to the information exchange by a quantum dot and vice-versa. We next observe that there is a reduction in circuit (CV) complexity too in the presence of excitations for small times.
Through a black hole into a new universe
Authors: Brandenberger Robert , Heisenberg Lavinia , Robnik Jakob
Published: October 2021

We show that an S-brane which arises in the inside of the black hole horizon when the Weyl curvature reaches the string scale induces a continuous transition between the inside of the black hole and the beginning of a new universe. This provides a simultaneous resolution of both the black hole and Big Bang singularities. In this context, the black hole information loss problem is also naturally resolved.
A dynamical system analysis of cosmic evolution with coupled phantom dark energy with dark matter
Authors: Chakraborty Soumya , Mishra Sudip , Chakraborty Subenoy
Published: October 2021

This work is an example of the application of the dynamical system analysis in the context of cosmology. Here cosmic evolution is considered in the background of homogeneous and isotropic flat FLRW spacetime with interacting dark energy and varying mass dark matter as the matter content. The DE is chosen as phantom scalar field with self-interacting potential while the DM is in the form of dust. The potential of the scalar field and the mass function of dark matter are chosen as exponential or power-law form or in their product form. Using suitable dimensionless variables, the Einstein field equations and the conservation equations constitute an autonomous system. The stability of the nonhyperbolic critical points is analyzed by using center manifold theory. Finally, cosmological phase transitions have been detected through bifurcation analysis which has been done by Poincaré index theory.
Absence of covariant singularities in pure gravity
Authors: Casadio Roberto , Kamenshchik Alexander , Kuntz Iberê
Published: October 2021

The assumptions of the Hawking–Penrose singularity theorem are not covariant under field redefinitions. Following the works on the covariant formulation of quantum field theory initiated by Vilkovisky and DeWitt in the 80s, we propose to study singularities in field space, where the spacetime metric is treated as a coordinate along with the other fields in the theory. From this viewpoint, a spacetime singularity might be just a singularity in the field-space coordinates, analogously to the standard coordinate singularities in General Relativity. Objects invariant under field-space coordinate transformations can then reveal whether certain spacetime singularity is indeed singular. We recall that observables in quantum field theory are scalar functionals in field space. Therefore, in principle, spacetime singularities corresponding to regular field-space curvature invariants would not affect physical observables. In this paper, we show that the field-space Kretschmann scalar for a certain choice of the DeWitt field-space metric is everywhere finite. This fact could be interpreted as an indication that no singularities actually exist in pure gravity for any gravitational action. In particular, all vacuum singularities of General Relativity result from an unhappy choice of field variables. The extension to the case in which matter fields are present, as required by singularity theorems, is left for future development.
MRI FINDINGS OF SACROILIAC JOINT IN ADULTS WITH CHRONIC LOW BACK PAIN
Authors: Dahmarde Hamid , Kiyani Motahare
Published: October 2021

Background: Low back pain is a common disease that has shown unspecified etiology in significant percentage of patients. In this study, the main purpose is determination of the frequency of Sacroiliac MRI findings in 18–45-year-old patients with chronic low back pain. Methods: This descriptive study was performed on 224 patients aged 18–45 years with chronic lumbar pain who referred to Imam Ali Hospital Imaging Center, Zahedan, Iran in 2018–2019. These patients were subjected to sacroiliac imaging. Data were analyzed by SPSS software and Chi-square test. Results: In this study, the frequencies of different findings related to sacroiliac joint were recorded: Bone marrow edema: 55(24%), transitional vertebra: 41(18%) fatty marrow deposition: 32 (14%), erosion:20(89%), sclerosis: 15(6%), osteitis condense ilii: 5(2%), accessory sacroiliac joint: 3(1%), abnormal segmentation: 2, spina bifida:2, malignant involvement:1. Out of 224 patients, 127 (56%) had undergone sacroiliac MRI which could be related to their low back pain, while these findings were ignored in the usual Lumbosacral imaging. Conclusions: The importance of sacroiliac MRI was ignored in the usual imaging of low back pain. It might be better to perform MRI as a routine in these patients.