bluuebunny/crossref_metadata_2025 huggingface dataset:
Research and development of visual numerical simulation software for transient process of hydropower station
Authors: Guo Wencheng , Zhou Jianzhong , Wang Bingbao
Published: June 2021

Transient process is the basis of the safe and stable operation of hydropower station. The calculation of transient process is realized by professional numerical simulation software. This paper presents the research and development of the visual numerical simulation software for transient process of hydropower station. The software is designed and developed based on the Java language and the Eclipse and IntelliJ IDEA development environment. The research and development thought contains five aspects. Firstly, the mathematical model for the transient process of hydropower station is established and the algorithm is adopted. The program for numerical simulation is designed. Secondly, based on the modularization design principle, the object modules and operating condition modules are designed and encapsulated. Thirdly, the user-oriented visual interface of the software is designed and programmed. The visual interface includes menu bar, toolbar and plotting area, which realize the drawing of topology of hydropower station, input of parameters, setting of calculation conditions and post-processing of calculation results. Fourthly, the foreground and background interaction based on graphic interface is achieved to realize the recognition of topology, automatic coding of object modules and transfer of foreground data. Finally, the mathematical model, algorithm, object modules, operating condition modules, visual interface and foreground and background interaction are integrated and the development of the visual numerical simulation software is completed. The visual numerical simulation software for transient process of hydropower station is a general software and has a friendly user interface. Test and application of practical engineering prove the correctness, reliability and precision of the software. The visual numerical simulation software provides a simple, practical and efficient tool for the calculation of transient process of hydropower station.
Turbine mode start-up simulation of a FSFC variable speed pump-turbine prototype – Part I: 1D simulation
Authors: Alligné S , Béguin A , Biner D , Münch-Alligné C , Hasmatuchi V , Hugo N , Avellan F , Dujic D , Nicolet C,
Published: June 2021

Variable speed hydroelectric units equipped with full size frequency converter (FSFC) offer high operational flexibility enabling fast operating point transitions which increase grid regulation capacities. The XFLEX HYDRO H2020 European research project aims to demonstrate flexibility of such technology at prototype scale. The Z’Mutt pumping station, part of the Grande Dixence hydroelectric scheme located in Switzerland, is one of the demonstrators focused on the FSFC technology with a new 5 MW reversible Francis pump-turbine which will be commissioned in 2021. This paper, divided in two parts, aims to simulate the turbine mode fast start-up sequence made possible with the use of a FSFC and to assess the unit damage by means of 1D and 3D CFD simulations. The part I of this paper presents the 1D hydraulic transient simulation results of start-up sequences of unit U5 considering both conventional fixed speed technology and variable speed technology. The time evolution of the unit’s operating point is used as input data for 3D CFD simulations of part II, aiming to assess the impeller damage. Different control strategies to use the FSFC for turbine mode start-up sequence are analysed. Advantages and limits of each strategy are discussed, and recommendation is made for the Z’Mutt prototype demonstrator.
One-dimensional numerical simulation of cavitation surge in pumping system considering cavity response delay
Authors: Watanabe S , Tsujimoto Y
Published: June 2021

Cavitation instabilities such as rotating cavitation and cavitation surge often occur in high speed turbopumps. In the present study, numerical simulation of cavitation surge, which numerically solves the one-dimensional momentum and continuity equations with modelled dynamic cavitation characteristics, is conducted. The phase lag of cavity response against the inlet pressure and the suction flow rate variations is modeled in the form of the first-order lag system considering that the frequency of cavitation surge is small. Differently from linear stability analysis made in our previous study, the equations are solved in time domain with retaining some of non-linear terms. The method is validated through the comparison with the stability analysis. Then the effect of phase lags in dynamic cavitation characteristics is examined.
Investigations on fatigue curves in dependency of water quality for nickel-martensitic steels
Authors: Leibing B , von Locquenghien F , Rückle D , Schellenberg G
Published: June 2021

With the need for flexible operation, Francis runners are exposed to various operating conditions outside the traditional operating range. To grant sufficient fatigue life, a deep knowledge of both loads and material behavior is mandatory. With the change in operation diverse stress amplitudes and number of cycles have to be considered for the comparison with fatigue curves. Hydro power turbines are exposed to possible corrosion attack due to the surrounding water environment, which is a relevant impact on the fatigue curves. Therefore an overview of parameters that influence the corrosivity will be given. From an evaluation of a database that contains water quality data of worldwide hydro power projects, different water qualities are defined to perform fatigue tests with the influence of a corrosive medium. For selected water qualities, preliminary material test results will be presented.
Turbine mode start-up simulation of a variable speed Francis pump-turbine prototype – Part II: 3-D unsteady CFD and FEM
Authors: Biner D. , Alligné S. , Hasmatuchi V. , Nicolet C. , Hugo N. , Avellan F. , Dujic D. , Münch-Alligné C.
Published: June 2021

The Z’Mutt pumping station, part of the Grande Dixence hydroelectric scheme, is one of the demonstrators of the XFLEX HYDRO project. A 5 MW reversible pump-turbine prototype equipped with a full-size frequency converter (FSFC) is used to investigate dynamic variable speed operation in pumping and generating mode. Since the FSFC converter is always connected to the electrical grid, the full rotational speed range of the motor-generator can theoretically be exploited. Furthermore, this technology enables fast operating point transitions and therefore increased grid regulation capacities. The advantages of the FSFC technology in generating mode are compared to a conventional fixed speed start-up with a variable speed start-up. The operating point trajectories are extracted from 1-D hydraulic transient simulations. Detailed hydrodynamic and structural aspects of the pump-turbine during the two start-up scenarios are further studied. Simplified unsteady 3-D CFD simulations and transient structural FEM analyses of the pump-turbine prototype are carried out to assess the harshness of the flow and to anticipate runner fatigue. The present work aims to point out potential mitigation of partial runner damages during start-up in generating mode using FSFC technology.
Measurement and simulation of the dynamic characteristics of plain and profiled annular seals
Authors: Kuhr M M G , Ludwig G , Pelz P F
Published: June 2021

The performance and reliability of turbomachinery is often limited by shaft vibrations induced by fluid forces of (i) plain or profiled annular seals, (ii) pistons and (iii) journal bearings. The rotordynamic coefficients namely, stiffness, damping and inertia of plain annular seals are in general calculated using the bulk-flow approach developed by Childs. However, when applying the calculation method to profiled gaps, especially those with non-symmetrical profiles, large differences between simulation and experimental data are reported. Furthermore, reliable experimental data as well as large databases including experimental and simulation results from a single author are limited. To overcome this, the paper introduces a unique active magnetic bearing test rig, built and operated at the Technische Universität Darmstadt as well as the corresponding simulation method to determine the rotordynamic influence of annular seals. An extensive experimental study is carried out investigating plain, symmetrically profiled and non-symmetrically profiled annular seals within the relevant parameter range for turbulent flow in pumps. The results are compared to the simulation results showing a significant influence of profiled gaps on the dynamic characteristics in comparison to plain annular seals. Furthermore, it is shown that symmetric and non-symmetric profiles have a different influence on the dynamic quantities inertia, damping and stiffness.
Velocity Measurements in Kaplan and Propeller Turbines: a review
Authors: Sotoudeh N , Raisee M , Cervantes M J
Published: June 2021

Complex geometry and flow regimes are present in different sections of hydraulic turbines and most operating conditions. In the past two decades, many pressure measurements have been performed on different sections. Such measurements do not reveal the details of the flow distribution. Velocity measurements are needed to obtain more detailed information. The aim of the present paper is to review the velocity measurements performed in hydraulic turbines, especially axial turbines, and highlight the remaining challenges according to the operating condition.
CFD analysis of flow pattern in S-Shape region for low specific speed Francis turbine
Authors: Kobayashi Katsutoshi , Tamura Yuta
Published: June 2021

In this research, a Francis turbine with low specific speed was analyzed by unsteady numerical simulation in case of S-Shape region appearing model test. It was found that S-Shape characteristics curve was caused by an increase of head. Firstly, the head was decreased in accordance with a decrease of flow rate. However, once a centrifugal force became larger, then a reverse flow appeared between guide vane and runner and the head was increased. And then, head was decreased with flow rate decreasing. In this research, operating conditions of flow rate were defined as three regions, first half of S-Shape region, just S-Shape region and last half of S-Shape region. The operating condition, where the head was decreased in accordance with the decrease of flow rate, was defined as the first half of S-Shape region. The operating condition, where the head was just being increased in accordance with the decrease of flow rate, was defined as the just S-Shape region. The operating condition after passing of the just S-Shape region was defined as the last half of S-Shape region. It was revealed that those three operating conditions showed a spectrum distribution of pressure fluctuation differently each other. A flow visualization analysis with numerical results was conducted to investigate the difference of pressure spectrum in three operating conditions. At the first half of S-Shape region, two groups of reverse flow were caused at chamber between guide vane and runner and revolving in same direction as runner rotation. At the just S-Shape, the reverse flows were circumferentially connected to build a long curved string. At the last half of S-Shape, the reverse flows were fully connected to build a round ring shape.
Analysis of Dynamic Stresses of Pump-Turbine Runner during Load Rejection Process in Turbine Mode
Authors: Chen Funan , Yang Xiaolong , Bi Huili , Mao Zhongyu , Luo Yongyao , Liujingshi  , Fan Hongang , Wang Zhengwei
Published: June 2021

During load rejection process, the rotation rate, head and discharge change a lot and the internal flow of the runner is complex, leading to fatigue cyclic loads on the runner. In some cases, fatigue cracks appear at the stress concentration location of the runner. This paper studied the dynamic stresses of a pump-turbine runner during load rejection process in turbine mode using finite element method. The hydraulic loads were obtained from CFD analysis, and the clearance flow was taken into consideration in the CFD simulation. The variation of performance characteristics was calculated through the one-dimensional method of characteristic (1D-MOC). The results show that the pressure on outer surfaces of runner changed the stress of the runner, and the rotation rate had a great influence on the dynamic stresses of the runner.
Parametric Design Tool for Development of a Radial Guide Vane Cascade for a Variable Speed Francis Turbine
Authors: Stojkovski Filip , Lazarevikj Marija , Markov Zoran
Published: June 2021

Hydropower as a part of the family of renewable energy sources represents an engineering and scientific field which inspires researchers to work on development of the systems and sub-systems in a way of optimizing the whole energy transformation process to obtain more efficient, flexible and reliable hydropower operation with the best possible water to energy ratio. This research is part of a Horizon 2020 HydroFlex project by the Norwegian University of Science and Technology (NTNU), where the main goal is development of a flexible hydropower generation. The guide vane cascade is one of the most crucial stationary sub-systems of the hydraulic turbine and is a subject of this study. Its re-design for obtaining a quality “flow-feeding” of a variable speed high head Francis turbine is developed. Having this goal in mind, a MATLAB code was generated, based on several key parameters, such as initial energy conditions as net head and turbine discharge at best efficiency point (BEP). Turbine runner geometrical constraints are taken into account during this process, while using recommendations for some initial guide vane calculations such as their number, inlet and outlet diameter, guide vane axis diameter, delivery angles etc. Using an inverse Euler turbine equation, the operating range of the turbine was calculated for a variable speed and discharge conditions, keeping the shock-free flow for all states at the runner’s inlet, as it is the most favourable inflow condition. For those operating points, the flow streamlines angles were obtained at the guide vanes leading and trailing edges. With an interpolating mathematical functions between the angles of the leading and trailing edges, the camber lines of the hydrofoils were obtained for further guide vane cascade geometry development. This algorithm can be implemented on any given runner geometry. The guide vane design is then exported into ANSYS Workbench for further numerical tests, such as CFD simulations for verifying the hydrodynamic characteristics and FEM analysis for verifying the structural integrity of this sub-system for variable speed operating conditions.
Numerical Investigation of flow instabilities in Speed No-Load operation of a Bulb turbine
Authors: Yamamoto K , Roubaty M , Morisod M , Coulaud M , Houde S
Published: June 2021

When operating in Speed-No-Load (SNL), turbines function at their synchronous rotating speed with a fraction of discharge at best efficiency point, ready for electrical grid connection. The flow in SNL condition is characterized by high swirling component leading to complex flow structures inside the runner, which generate wide-band pressure fluctuations. When operating in SNL condition, high specific speed turbines, such as axial turbines, can be damaged by significant pressure oscillations attributed to rotating vortex phenomena, alike rotating stall. However, understanding the fundamental flow dynamics behind the phenomena in SNL condition remains challenging due to the stochastic nature of flow. The present research highlights unsteady flow characteristics and flow instabilities in SNL condition of a bulb turbine by URANS simulations based on scale-resolving techniques. The simulation results provide evidence that the development of a rotating vortex array in precession with the runner is a major source of pressure oscillations and torque fluctuations in SNL operation of this bulb turbine.
Influence of the elbow shape on the unsteady pressure field in decelerated swirling flows
Authors: Muntean S , Moş DC , Szakal RA , Bosioc AI , Susan-Resiga R
Published: June 2021

The induced flow instabilities are developed in the draft tube cone of the hydraulic turbines leading to the pressure fluctuations with negative impact on the mechanical components lifetime. Usually, two components (rotating and plunging) are discriminated in the unsteady pressure field induced by the swirling flow in the draft tube cone. The rotating component is associated with the precession motion of the flow instabilities (e.g. vortex rope) while the plunging part corresponds to the interaction of the swirling flow with the elbow. Extensive experimental investigations were carried out on Timisoara Swirl Generator test case in order to examine the influence of the elbow shape on the unsteady pressure field. Two elbow shapes (90° S shape elbow and 90° sharp heel) are selected to investigate their influence on the unsteady pressure field. Several geometrical configurations with pipe extensions placed between the cone and the elbow are considered for each elbow shape to determine the response of the hydraulic circuit. Two unsteady pressure signals located in opposite positions are measured on four levels placed along the cone. The Fourier spectra are determined for discriminated time series identifying both rotating and plunging components. Then, the ratio between the frequencies of the plunging and the rotating components is obtained for both elbow shapes in relation to the pipe length placed between the cone and the elbow. It is clear that the shape of the elbow and the distance between the cone and the elbow lead to a significant influence on the response of the hydraulic circuit.
Geometric parameters of influence on rotor stator interaction in radial hydraulic turbines
Authors: Nennemann B , Afara S , Monette C , Braun O
Published: June 2021

Numerical methods for the prediction of the hydraulic forcing from rotor stator interaction (RSI) in hydraulic turbines as well as the corresponding methods to calculate mechanical dynamic stresses are mature and well-established in the industry. The geometric factors influencing RSI are generally known, but little information is available on the quantification of these factors with respect to RSI forcing. We present relative quantifications of four geometric factors on RSI forcing expressed as dynamic blade torque. The factors are the blade leading edge lean, the radial distance between guide vane trailing and runner leading edges, the phase between adjacent runner channels as a function of number of guide vanes and blades, and finally the number of guide vanes independently of their effect on the phase. RSI pressure pulsations on the stator in the vane-less space between guide vanes and runner show a different tendency with the variation of the blade number compared to the dynamic blade torque. This indicates that dynamic pressure measurements in the vane-less space are not a good indicator for dynamic forcing on the runner blades.
Pump-turbine Rotor-Stator Interaction Induced Vibration: Problem Resolution and Experience
Authors: Zhang F , Lowys PY , Houdeline JB , Guo XD , Hong P , Laurant Y
Published: June 2021

Pressure pulsations induced by rotor-stator interaction (RSI) phenomenon are one of the major sources of excitation resulting in severe vibrations of pump-turbines and powerhouses. By now, many articles focus mainly on the RSI mechanism by methods of theoretical analysis, fluid-structure calculation and model test verification. There are few reports published on equipment and powerhouse vibrations induced by RSI. Therefore, in this paper we took a real RSI induced problem at Zhanghewan (ZHW) pumped storage power plant (PSPP). We employed frequency spectrum technology on signals of powerhouse vibrations and pressure pulsations in stable and transient processes, combined eigen-frequency measurement and numerical calculation of powerhouse localities, and then confirmed that partial powerhouse resonated with RSI induced pressure pulsation in the vaneless area (gap between guide vanes and runner blades). We statistically evaluated the relationship between the ratio of guide vane pitch diameter D0 to the high-pressure runner diameter D1 and vaneless area pressure pulsation from many PSPPs in China, and proposed solutions that new runner should use. The runner alteration work was successful. Model tests and field measurements show that vaneless pressure pulsation decreases and the powerhouse shows acceptable vibration levels. Many experiences were accumulated during this work, including that from an engineering perspective by enlarging the vaneless area it is possible to lower RSI induced pressure vibrations. Also, much attention should be paid on local anti-vibration calculations in the powerhouse designing period. Our research and review provide a new perspective for designing, refurbishing, rehabilitating of pump-turbines.
Research on Modeling and Control Strategy of Hydraulic Turbine Governing System Based on Improved Genetic Algorithm
Authors: Jiang Xiaoping , Chen Xiaofei , Wang Zhengwei
Published: June 2021

The mathematical model of the turbine governing system is obtained by modeling analysis. Under the premise of this model, the improved genetic algorithm is used to optimize the parameters in the parameter identification of the turbine governing system, and the high-precision parameter identification of the turbine governing system is realized, and an accurate mathematical model of the turbine governing system is established. In terms of control strategy, through theoretical analysis of conventional PID, fuzzy control and genetic algorithm, a fuzzy PID control based on genetic algorithm optimization (GA-fuzzy PID) is designed to realize the adaptive and adjustment ability of PID control. Compared with the traditional PID control, it has better control effect, and it is easier to make the turbine adjustment system achieve stability, quickness and accuracy.
Comparisons of vortical flow and cavitation inside a Francis turbine with different draft tubes
Authors: Geng Chen , Zhang Ruizhi , Tsujimoto Yoshinobu , Nishi Michihiro , Luo Xianwu
Published: June 2021

It is well known that strong pressure fluctuation will occur in the draft tube of a Francis turbine operated under part-load operation. The pressure fluctuation is usually due to the vortex rope as well as cavitation. However, the vortical flow and pressure field are dependent on the geometry of draft tube of Francis turbine. In this study, hydraulic performance and pressure fluctuation have been tested for a model Francis turbine. The internal flow for the turbine is investigated numerically. It is confirmed that the numerical results predict reasonably the hydraulic performance and the pressure fluctuation due to vortex rope at part-load operation.

For a better understanding of the vortical flow in the model turbine, a conical draft tube is used instead of the conventional elbow draft tube. The vorticity transport equation is applied to analyze the vortex evolution inside Francis turbine based on the unsteady flow simulation. The flow mechanism of the vortex rope and pressure fluctuation with different draft tubes is discussed. It is shown that both cavitation and the bending structure influence the vortex rope, which will cause a significant difference in the distribution of pressure fluctuation.
Evaluation of the effects of shear stress on crucian carps passing through turbines
Authors: Meng Long , Wang Wanpeng , Li Tieyou , Liao Cuilin , Zhao Lice , Chen Ying
Published: June 2021

Turbine-passed fish is inevitably exposed to one or more physical forces, such as fast pressure change, blade strikes and shear stress, which can lead to injury or fatalities. The injury mechanisms of these forces to fish and related criteria are necessary for fish-friendly-turbine design and optimization. The effects of shear stress on crucian carps are studied in a specially designed experimental system. Crucian carps are exposed to a submerged water jet at velocities ranging from 5m/s to 20m/s. High-speed, high-resolution digital videos of the exposure process was recorded for motion-tracking analysis. Fish sizes, flow directions and water jet velocities are key factors considered during the tests. Injury rate, degree of severity, site of trauma, and death rate of crucian carps after tests were studied according to repeated tests with different factors. Injuries such as shedding of fish scales, tearing of gill cover, laceration of eyeballs are observed at different water jet velocity and with different size of crucian carps. The injury mechanisms were concluded and design criteria for fish-friendly-turbine are proposed according to the study.
Numerical Simulation and Research of the Axial Flow Fish-friendly Turbine in Plateau Area
Authors: Yang Chunxia , Xu Ding’e , Zhang Qianxu , Zhu Shuangju , Zhao Lei
Published: June 2021

Based on the design methods of fish friendly hydraulic turbines at home and abroad and traditional hydraulic turbines, this paper designs an axial flow fish friendly hydraulic turbine in plateau area by using Unigraphics NX. The steady-state simulation of the turbine is carried out by fluent, and the energy characteristics of the three blade runner are analyzed. Through the transient computation, the pressure fluctuation characteristics in the leafless area of the turbine with guide vane opening of 18.2° and 14.2° are studied, and the fish passing characteristics are analyzed. Compared with the evaluation criteria of fish friendly water turbine, the variation rate of pressure obtained is less than 550.3kpa/s, which meets the design criteria of fish friendly water turbine and basically meets the demand of fish passing down the dam.
Novel Hydraulic Turbine Governing System Based on Digital Cartridge Valve Technology
Authors: Wang Cong , Wang De-kuan , Zhang Jian-ming
Published: June 2021

Digital cartridge governor, as a new direction of hydraulic turbine governor control, has been applied in engineering practice, but its relative theory and engineering application research are few. The engineering application of novel hydraulic turbine governing system based on digital cartridge valve technology is taken as the research object in this paper. Combining theory with engineering application, control strategies and rules of the digital cartridge turbine governor in key concerns of engineering applications such as closed-loop power regulation, isolated grid operation, the low-frequency de-excitation and the over-speed of load rejection of bulb turbine units are discussed, and engineering applications of digital cartridge turbine governor are summarized, which can be used for reference to solve some problems in the application of governor.
Botulinum Toxin to Improve Lower Blepharoplasty Scar: A Double-Blinded, Randomized, Vehicle-Controlled Clinical Trial
Authors: Huang Yau-Li , Wallace Christopher Glenn , Hsiao Yen-Chang , Lee Mei-Ching , Huang Jung-Ju , Chang Frank Chun-Shin , Chen Zung-Chung , Hu Sindy , Chen Jyh-Ping
Published: June 2021

Background

Lower blepharoplasty is a common cosmetic operation that relies on minimal postoperative scarring, but Asian patients are at higher risk than Caucasians for hypertrophic and/or widened scars. Botulinum toxin type A (BTX) injections are widely employed to alleviate dynamic facial rhytids and also can improve scar quality by reducing scar tension. The authors assessed whether simultaneous transcutaneous lower blepharoplasty and BTX injections could improve subciliary scar quality.

Objectives

The objective of this study was to assess whether simultaneous transcutaneous lower blepharoplasty and BTX injections could improve subciliary scar quality.

Methods

This is a prospective, randomized, vehicle-controlled, double-blinded clinical trial. Between May 2015 and May 2018, 40 adults who underwent bilateral transcutaneous lower blepharoplasties were randomized to receive BTX (n = 20) or vehicle (normal saline; n = 20) injections into the lateral orbicularis oculi muscle immediately after wound closure. Vancouver Scar Scale, Visual Analogue Scale, and photographic scar width measurements at 3 reference points were recorded at the final clinical follow-up.

Results

Thirty-seven patients completed the trial. Vancouver Scar Scale and Visual Analogue Scale scores in the experimental and vehicle control groups were similar, but scar widths in the experimental group at all measured points were significantly narrower than in the vehicle control group (P < 0.001, P = 0.027, and P < 0.001 at each measured point, respectively).

Conclusions

Transcutaneous lower blepharoplasty scars in Asians can be significantly narrowed by simultaneous BTX injections without additional complications.

Level of Evidence 4
COSMIC Cancer Gene Census 3D database: understanding the impacts of mutations on cancer targets
Authors: Alsulami Ali F , Torres Pedro H M , Moghul Ismail , Arif Sheikh Mohammed , Chaplin Amanda K , Vedithi Sundeep Chaitanya , Blundell Tom L
Published: June 2021

Mutations in hallmark genes are believed to be the main drivers of cancer progression. These mutations are reported in the Catalogue of Somatic Mutations in Cancer (COSMIC). Structural appreciation of where these mutations appear, in protein–protein interfaces, active sites or deoxyribonucleic acid (DNA) interfaces, and predicting the impacts of these mutations using a variety of computational tools are crucial for successful drug discovery and development. Currently, there are 723 genes presented in the COSMIC Cancer Gene Census. Due to the complexity of the gene products, structures of only 87 genes have been solved experimentally with structural coverage between 90% and 100%. Here, we present a comprehensive, user-friendly, web interface (https://cancer-3d.com/) of 714 modelled cancer-related genes, including homo-oligomers, hetero-oligomers, transmembrane proteins and complexes with DNA, ribonucleic acid, ligands and co-factors. Using SDM and mCSM software, we have predicted the impacts of reported mutations on protein stability, protein–protein interfaces affinity and protein–nucleic acid complexes affinity. Furthermore, we also predicted intrinsically disordered regions using DISOPRED3.
Markets as ecological networks: inferring interactions and identifying communities
Authors: Emary Clive , Fort Hugo
Published: June 2021

Financial markets are paradigmatic examples of complex systems and have been compared to ecological networks in which different species (firms) interact and co-evolve. A central object governing species dynamics in ecology is the community matrix, whose elements are closely related to pairwise interspecific interaction coefficients. Using this ecological analogy we propose a method, based on the Maximum Entropy (MaxEnt) principle, that allows us to infer candidates for an economic community matrix from time series data of market values. To assess the usefulness of this picture, we construct community matrices for a set of companies belonging to the Fortune 500 list and perform a community analysis on the resultant networks. This analysis shows these networks to strongly reflect the known industry groupings of the firms. We conclude therefore that our community matrices capture non-trivial information about the interaction of firms, not immediately apparent from the covariance of market values. We anticipate our approach being useful in elucidating further aspects of market structure, as well as forming the basis of forecasting market dynamics.
Spatiotemporal and seasonal dynamics in the microbial communities of a landfill-leachate contaminated aquifer
Authors: Abiriga Daniel , Jenkins Andrew , Alfsnes Kristian , Vestgarden Live Semb , Klempe Harald
Published: June 2021

The microbiome of an aquifer contaminated by landfill leachate and undergoing intrinsic remediation was characterised using 16S rRNA metabarcoding. The archaeal/bacterial V3–V4 hypervariable region of the 16S rRNA gene was sequenced using Illumina MiSeq, and multivariate statistics were applied to make inferences. Results indicate that the aquifer recharge and aquifer sediment samples harbour different microbial communities compared to the groundwater samples. While Proteobacteria dominated both the recharge and groundwater samples, Acidobacteria dominated the aquifer sediment. The most abundant genera detected from the contaminated aquifer were Polynucleobacter, Rhodoferax, Pedobacter, Brevundimonas, Pseudomonas, Undibacterium, Sulfurifustis, Janthinobacterium, Rhodanobacter, Methylobacter and Aquabacterium. The result also shows that the microbial communities of the groundwater varied spatially, seasonally and interannually, although the interannual variation was significant for only one of the wells. Variation partitioning analysis indicates that water chemistry and well distance are intercorrelated and they jointly accounted for most of the variation in microbial composition. This implies that the species composition and water chemistry characteristics have a similar spatial structuring, presumably caused by the landfill leachate plume. The study improves our understanding of the dynamics in subsurface microbial communities in space and time.
Effects of Synonymous Mutations beyond Codon Bias: The Evidence for Adaptive Synonymous Substitutions from Microbial Evolution Experiments
Authors: Bailey Susan F , Alonso Morales Luz Angela , Kassen Rees
Published: June 2021

Synonymous mutations are often assumed to be neutral with respect to fitness because they do not alter the encoded amino acid and so cannot be “seen” by natural selection. Yet a growing body of evidence suggests that synonymous mutations can have fitness effects that drive adaptive evolution through their impacts on gene expression and protein folding. Here, we review what microbial experiments have taught us about the contribution of synonymous mutations to adaptation. A survey of site-directed mutagenesis experiments reveals the distributions of fitness effects for nonsynonymous and synonymous mutations are more similar, especially for beneficial mutations, than expected if all synonymous mutations were neutral, suggesting they should drive adaptive evolution more often than is typically observed. A review of experimental evolution studies where synonymous mutations have contributed to adaptation shows they can impact fitness through a range of mechanisms including the creation of illicit RNA polymerase binding sites impacting transcription and changes to mRNA folding stability that modulate translation. We suggest that clonal interference in evolving microbial populations may be the reason synonymous mutations play a smaller role in adaptive evolution than expected based on their observed fitness effects. We finish by discussing the impacts of falsely assuming synonymous mutations are neutral and discuss directions for future work exploring the role of synonymous mutations in adaptive evolution.
The law of the global economy and the spectre of inequality
Authors: Venzke Ingo
Published: June 2021

Drawing on my inaugural lecture, I argue that the spectre of inequality haunts international law. The presence of the spectre first of all draws attention to what is rotten in the global economic order: how the law of the global economy has contributed to high levels of inequality while, at the same time, abdicating responsibility for it. Second, like all spectres, international law’s spectre of inequality is animated by a spirit, the spirit of social justice. It points to forsaken paths, lost memories and conjures up past possibilities that were not realized. Third, the spectre endures unless we give in and break with current repetitions. It directs those in search of progressive change towards productive contradictions within global order. Those contradictions are indeed carriers of hope. They offer reason to believe that the future is open. Engaging with the spectre of inequality in international law turns out to be much less daunting than failing to do so.
A theoretical model of the near-surface shear layer of the Sun
Authors: Jha Bibhuti Kumar , Choudhuri Arnab Rai
Published: June 2021

The Sun has a near-surface shear layer (NSSL), within which the angular velocity decreases rapidly with radius. We provide an explanation of this layer based on the thermal wind balance equation. Since convective motions are not affected by solar rotation in the top layer of the convection zone, we argue that the temperature falls at the same rate at all latitudes in this layer. This makes the thermal wind term very large in this layer and the centrifugal term has also to become very large to balance it, giving rise to the NSSL. From the values of differential rotation Ω(r < rc, θ) at radii less than a radius rc, we can calculate the temperature difference ΔT(r, θ) with respect to the standard solar model at different points of the convection zone by making use of the thermal wind balance equation. Then, we again use this equation in the top layer to calculate Ω(r > rc, θ) there from ΔT(r, θ). We carry on this exercise using both an analytical expression of the differential rotation and the actual data provided by helioseismology. We find that our theoretical results of the NSSL match the observational data reasonably well for rc ≈ 0.96R⊙, giving an estimate of the radius till which the convective motions are affected by the solar rotation.
“Disruptive Technology” in Spine Surgery and Education: Virtual and Augmented Reality
Authors: Godzik Jakub , Farber S Harrison , Urakov Timur , Steinberger Jeremy , Knipscher Liza J , Ehredt Ryan B , Tumialán Luis M , Uribe Juan S
Published: June 2021

BACKGROUND

Technological advancements are the drivers of modern-day spine care. With the growing pressure to deliver faster and better care, surgical-assist technology is needed to harness computing power and enable the surgeon to improve outcomes. Virtual reality (VR) and augmented reality (AR) represent the pinnacle of emerging technology, not only to deliver higher quality education through simulated care, but also to provide valuable intraoperative information to assist in more efficient and more precise surgeries.

OBJECTIVE

To describe how the disruptive technologies of VR and AR interface in spine surgery and education.

METHODS

We review the relevance of VR and AR technologies in spine care, and describe the feasibility and limitations of the technologies.

RESULTS

We discuss potential future applications, and provide a case study demonstrating the feasibility of a VR program for neurosurgical spine education.

CONCLUSION

Initial experiences with VR and AR technologies demonstrate their applicability and ease of implementation. However, further prospective studies through multi-institutional and industry-academic partnerships are necessary to solidify the future of VR and AR in spine surgery education and clinical practice.
Enhanced sensitivity to optimistic cues is manifested in brain structure: a voxel-based morphometry study
Authors: Aue Tatjana , Dricu Mihai , Singh Laura , Moser Dominik A , Kotikalapudi Raviteja
Published: June 2021

Recent research shows that congruent outcomes are more rapidly (and incongruent less rapidly) detected when individuals receive optimistic rather than pessimistic cues, an effect that was termed optimism robustness. In the current voxel-based morphometry study, we examined whether optimism robustness has a counterpart in the brain structure. The participants’ task was to detect two different letters (symbolizing monetary gain or loss) in a visual search matrix. Prior to each onset of the search matrix, two different verbal cues informed our participants about a high probability to gain (optimistic expectancy) or lose (pessimistic expectancy) money. The target presented was either congruent or incongruent with these induced expectancies. Optimism robustness revealed in the participants’ reaction times correlated positively with gray matter volume (GMV) in brain regions involved in selective attention (medial visual association area, intraparietal sulcus), emphasizing the strong intertwinement of optimistic expectancies and attention deployment. In addition, GMV in the primary visual cortex diminished with increasing optimism robustness, in line with the interpretation of optimism robustness arising from a global, context-oriented perception. Future studies should address the malleability of these structural correlates of optimism robustness. Our results may assist in the identification of treatment targets in depression.
Crossing Borders: Exploring the Role of School Social Workers in Immigrant-Serving Schools
Authors: Sosa Leticia Villarreal , Roth Benjamin , Rodriguez Sophia
Published: June 2021

Anti-immigrant rhetoric increasingly depicts immigrants as undeserving, but schools are social institutions where these perceptions can be challenged and, ideally, where inequities confronting immigrant students can be ameliorated. Existing research suggests that teachers and administrators are central to this task, but it also raises questions about the role of other personnel in immigrant-serving schools. Drawing on the concept of nepantlera, this study examines how school social workers (SSWs) pursue equity for immigrant students by challenging intersecting power structures. The authors present preliminary findings that attest to the importance of nepantleras for SSWs and the importance of SSWs for immigrant-serving schools.
When things go wrong
Authors: Rimmer John
Published: June 2021

Legal arrangements carry their own risks. The courts and legislatures have had centuries to get trust law right, but when foundations were introduced in the Channel Islands and the Isle of Man around ten to twelve years ago, there was a chance to short-cut much of that incremental development, and to use much of the trust and company law experience.

It was planned that foundations, in common law jurisdictions, would not be seen merely as trusts by another name. They were designed closely to resemble the civil law paradigm, in particular having legal personality, and the legislation made clear that they had different characteristics from trusts.

This article looks at the effective oversight of foundations in the Isle of Man, drawing on experiences in Jersey.
VI The Sixteenth Century: Excluding Drama after 1550
Authors: Davies Abe , Wood Richard
Published: June 2021

This chapter has three sections: 1. General; 2. Sidney; 3. Spenser. Section 1 is by Abe Davies; sections 2 and 3 are by Richard Wood.
Moderate Hyperbilirubinemia Improves Renal Hemodynamics in Angiotensin II‐Dependent Hypertension
Authors: Stec David E. , Vera Trinity
Published: June 2021

We have previously demonstrated that moderate hyperbilirubinemia decreases blood pressure in Angiotensin (Ang) II‐dependent hypertension through mechanisms that decrease oxidative stress and increase nitric oxide levels. The goal of the present study was to examine the effect of moderate hyperbilirubinemia on glomerular filtration rate (GFR) and renal blood flow (RBF) in a mouse model of Ang II hypertension. Mice were made moderately hyperbilirubinemic by treatment with 1) indinavir or 2) morpholino antisense oligonucleotides directed against hepatic UGT1A1. Levels of unconjugated bilirubin averaged 0.57 ± 0.07, 0.92 ± 0.07, and 1.28 ± 0.1 mg/dL (n=4) in control, indinavir, and antisense treated mice, respectively. GFR and RBF were measured in mice after implantation of an osmotic minipump delivering Ang II at a rate of 1 μg/kg/min. GFR was measured by continuous infusion of I125‐iothalamate on days 7–11 of Ang II infusion in conscious mice. RBF was measured on day 10 of Ang II infusion in anesthetized mice. Treatment with either indinavir or UGT1A1 antisense significantly increased GFR in Ang II infused mice 1.2 ± 0.1, 1.9 ± 0.2, and 1.9 ± 0.1 ml/min/g kidney weight (n=4) in non‐treated, indinavir, and antisense treated mice, respectively. Next, we examined the effect of moderate hyperbilirubinemia on RBF in Ang II infused mice. Ang II infusion significantly decreased RBF and this decrease was normalized by moderate hyperbilirubinemia with RBF averaging 5.2 ± 0.5, 3.8 ± 0.2, and 4.8 ± 0.3 ml/min/g kw (n=4) in control, Ang II, and Ang II+indinavir treated mice, respectively. These results indicate that improvement of renal hemodynamics may be a mechanism by which blood pressure is lowered with moderate hyperbilirubinemia in this model. This study was supported by NIH grant HL‐088421.
Overexpression of cyclin‐dependent kinase (CDK) inhibitors p21 and p27 is a common mechanism of experimental duodenal ulcer and ulcerative colitis
Authors: Paunovic Brankica , Khomenko Tetyana , Deng Xiaoming , Xiong Ximing , Sandor Zsuzsanna , Szabo Sandor
Published: June 2021

Recently we demonstrated that increased expression of cyclin‐dependent kinase inhibitors p21 and p27 is an early event in duodenal ulceration (DU) induced by cysteamine or mepirizole and in indomethacin‐caused gastric erosions. We hypothesized that overexpression of p21, p27 and p16 may be involved in the mechanisms of mucosal damage in both DU and ulcerative colitis (UC). To compare the effect of chemically‐induced injury in duodenal and colonic mucosa, Sprague‐Dawley rats were treated with cysteamine (85 mg/100 g, intragastrically) or with 6% iodoacetamide (0.1 ml, intracolonically). Animals were euthanized at 0.5, 2, 6, 12, 24 hr after treatment. Mucosal scrapings of proximal duodenum and distal colon were used for RNA isolation; p16, p21 and p27 were detected by Real‐time polymerase chain reaction. The results demonstrated that cysteamine enhanced duodenal p21 and p27 mRNA expression at 2 hr by 2.9‐ and 4.6‐fold, respectively. In colonic mucosa iodoacetamide increased p21 by 4.2‐fold and p27 expression by 1.5‐fold. Expression of p16 changed in neither DU nor UC.

Conclusions

1) Expressions of p21 and p27 were significantly increased in rat duodenal and colonic mucosa in the early stages of DU and UC formation. 2) Thus, both p21 and p27 but not p16 seem to be a common mechanism involved in the pathogenesis of DU and UC.

(This study was supported by Dept of Veterans Affairs, Medical Research Service Merit Reviews)
Diminazene Aceturate Is an ACE2 Activator and a Novel Antihypertensive Drug
Authors: Gjymishka Altin , Kulemina Lidia V , Shenoy Vinayak , Katovich Michael J , Ostrov David A , Raizada Mohan K
Published: June 2021

Emerging evidence suggests that ACE2 could be a new therapeutic target for cardiovascular disease (CVD) and hypertension. In this study, we used a molecular docking strategy combined with in vitro functional screening to search for novel ACE2 activators in support of this concept. Enzymatic assays with top‐scoring compounds demonstrated that diminazene aceturate (DIZE), a known antiprotozoal drug used in humans, acts as a potent activator of ACE2. DIZE caused a dose‐dependent increase in ACE2 activity and a maximal increase of 2.5 fold (Vmax) was observed with 50 μM. Intravenous administration of DIZE in WKYs and SHRs caused a transient and dose‐dependent decrease in mean arterial pressure (MAP). Although, DIZE decreased MAP in both strains of rats, its efficacy was significantly higher in the SHRs; a dose of 5 mg/kg of DIZE triggered a MAP reduction of 50±9 mmHg in WKY rats (n=6) compared to 85±11 mmHg in SHRs (n=6). In addition, chronic administration of DIZE at 15 mg/kg/day for three weeks in SHRs caused a modest decrease in MAP (from 136±3 to 124±6 mmHg, p<0.05). This was associated with a reduction in the heart weight to body weight ratio (3.8±0.004 in control versus 3.6±0.018 in DIZE treated, p<0.005) and myocardial fibrosis.

These data suggest that DIZE may serve as a lead compound for the discovery of next generation of drugs for the treatment of CVD and hypertension.

This work was funded by NIH grant HL56921.