bluuebunny/crossref_metadata_2025 huggingface dataset:
Mixed-Integer Programming for Optimizing Well Positions
Authors: Kuvichko Alexander , Ermolaev Alexander
Published: September 2020

The objective of this study is to design advanced methods of integer programming to optimize well positioning on oil and gas fields. In this paper we present a significant modification of new iterative method of solving Boolean and integer programming problems. This algorithm solves not just a static well position optimization, but a dynamic (in time) optimization of newly drilling well positions. These algorithms are suitable for non-regular well location problems when no strong pattern was defined. We have modified and improved an existing technology to optimize producers’ non-regular positions. Instead of running an exhausted search for all possible cases and defining the objective function value for each case (with or without the use of a hydrodynamic simulator), we designed a special iterative procedure. By increasing the number of cases and involving high-performance computing, we can estimate the global optimal point. Special types of Boolean constraints help to take into account existing wells or free of wells zones. Thus, we can solve optimization problems in time, taking into account recently placed wells.

We implemented designed algorithms on models with properties similar to real oilfields, where the number of wells per each problem is from ones to tens, like models of well pads or platforms. We compare different distance criteria based on some common engineering approaches. Optimal solutions of formulated problems are good as initial points for other iterative, gradient-based algorithms of well location problems. We present results of implementations for several cases and describe their optimality. Cases that we present include not just static optimal well positions, but a solution of dynamic problems. We first select a small number of wells to be placed and run the procedure. After drilling and putting into operation of first wells, we solve the optimization problem for further producers to be drilled. We discuss cases when it is rational to use this procedure instead of using a regular well pattern.
Optimization of Carbonate Heavy Oil Reservoir Development Using Surfactant Flooding: from Laboratory Screening to Pilot Test
Authors: Varfolomeev Mikhail Alexeevich , Ziniukov Rustam Anverovich , Yuan Chengdong , Khairtdinov Ruslan Kamilevich , Sitnov Sergey Andreevich , Sudakov Vladislav Anatolevich , Zhdanov Maxim Vladimirovich , Mustafin Aidar Zamilevich , Usmanov Sergey Anatolevich , Sattarov Aidar Ildarovich , Glukhov Mikhail Sergeevich
Published: September 2020

Bashkirian reservoir is a heavy oil fractured carbonate reservoir. It has a low temperature (23 ℃) and an ultra-high salinity (217.5 g/L). The low injectivity is the main problem that limits the efficient development of this reservoir. Hot water injection has been tried to solve this problem, but it did not work. The purpose of this work is to find an effective surfactant system for high salinity condition to increase the injectivity during water flooding. This paper presents the whole process from laboratory screening and numerical simulation to pilot test. In laboratory, ten surfactants were evaluated by measuring interfacial tension (IFT) and wettability change. For each surfactant, three concentrations were studied to obtain the optimal surfactant formulation. The optimal surfactants were used for filtration experiments to evaluate the effect of surfactant on the injectivity and oil displacement efficiency. The effect of the best surfactant was assessed by reservoir numerical simulation at the field scale. Eventually, the pilot test was implemented to test the effectiveness of surfactant injection. According to the ability to reduce IFT and change the wettability, oil displacement efficiency, the capacity of reducing injectivity, and production performance, as well as considering the cost and accessibility of surfactant, one nonionic surfactant was eventually chosen for pilot test in the oilfield.

The pilot test results show that this nonionic surfactant shows a very good effect on improving water injectivity. After the injection of surfactant, the wellhead pressure and downhole pressure were reduced from 40 at and 171.5 at to 24 at and 153.4 at), respectively. Surfactant injection increased additional oil production of about 1094 tones. The good effect of this nonionic surfactant showed in pilot test makes it a good candidate for wide application under high salinity condition to improve well injectivity as well as oil displacement efficiency in the case of complex heavy oil carbonate deposits.
In-Situ Channelization Model for Hydraulic Fracturing Simulation
Authors: Ivanov Maxim Grigorievich , Kaprielova Ksenia Mikhailovna , Starkov Ilya Andreevich , Romanovskii Rostislav Vladimirovich , Bannikov Denis Viktorovich , Kuznetsov Dmitry Sergeevich
Published: September 2020

In-Situ Channelization (ISC) phenomenon comprises a segregation of proppant and fiber-laden slurry in a hydraulic fracture during fracture closure. The segregation can lead to the creation of highly conductive open channels in the proppant pack and can significantly alter the fracture conductivity. Simulating ISC in a fracturing simulator can help maximize channeled areas, thus suggesting a higher production. The nature of ISC represents the slurry bridging at static conditions due to wall roughness and heterogeneities in proppant and fiber distribution. We demonstrate the development of the static bridging model, which we refer to as anchoring. The model is based on the physical principles, namely the force balance. The parameters governing the phenomenon include slurry composition, temperature, fracture walls surface roughness and orientation. Pixel-type approach to laboratory testing is introduced, which aids in the simplification of the model description and the implementation. Fracture waviness and roughness were found to affect the channelization, with fracture inclination angle being the most contributing factor. The model was extended to high temperatures, allowing simulations in the whole working ranges. Verification and validation showed fairly good reproduction of experimental data with the model, with tolerance of the anchoring event determination being within 5 ppt of fiber concentration. Simulations of hydraulic fracturing in the fracturing simulator with ISC model enabled revealed that ISC phenomenon has significant effect in treatments with low viscous fluids (e.g., linear gel or slick water). Meanwhile the effect diminishes as the reservoir temperature increases.
Utilizing Machine Learning Methods to Estimate Flowing Bottom-Hole Pressure in Unconventional Gas Condensate Tight Sand Fractured Wells in Saudi Arabia
Authors: Al Shehri Fahad Hassan , Gryzlov Anton , Al Tayyar Tayyar , Arsalan Muhammad
Published: September 2020

Installation of production tubulars is a critical job that has a direct impact on the overall productivity of the well. Thus, it is equally significant to predict the accurate flowing bottom-hole pressure (FBHP) in order to garner utmost benefits from the system by constructing the right vertical lift performance (VLP) curves. In fact, constructing the accurate VLP curves helps us identify the liquid loading times of wells and hence be able to predict when to install velocity strings or different artificial lift systems. For years, efforts have been made into developing mechanistic models and correlations to predict FBHP. However, all present correlations are developed under laboratory conditions and each have their own limitations for specific types of flow regimes. Mechanistic models integrate the physics of downhole conditions and yet they do not provide accurate results for FBHP. Therefore, artificial neural network (ANN), functional networks (FNN), and long-short term memory (LSTM) models were utilized in this paper. The designed models have been validated over a diverse range of data sets. More than 30,000 data points were collected from various wells with wide range of inputs. The inputs utilized in the AI models are from daily flowback data including wellhead pressure, wellhead temperature, true vertical depth, fluid specific gravity, chloride content, watercut, fluid rates, and water gas ratio. The data were then split as per the ratio of 4:1 for training and testing in order to generate accurate results. Then, the models were tested on other new well to test their accuracy. ANN model has proven to be the most accurate machine learning model and therefore, the results from the designed model were compared with the results of existing empirical correlations and it was evident that AI model outperformed them in terms of average absolute percent error (AAPE), and correlation coefficient (CC).
Digital Rheology of High Viscosity Friction Reducers
Authors: Inozemtseva Elizaveta Andreevna , Kaprielova Ksenia Mikhailovna , Ivanov Maxim Grigorievich
Published: September 2020

High-viscosity friction reducer (HVFR) fluid systems are increasingly used in hydraulic fracturing operations to achieve economic and technical objectives. As with other fracturing fluids, HVFR system performance is tied to rheological properties, which, on their own, are strongly dependent on water salinity.

A novel approach applies digital technology to HVFR rheology modeling for fluid performance prediction in a wide range of water compositions. The proposed model is an effort to digitize and model rheology for increased operational efficiency. It has several remarkable differentiations, including model sensitivity to polymer loading, temperature, and water salinity.
Applying Machine Learning Methods to Exploit Unprofitable Reserves
Authors: Vanina Anastasiia Sergeevna , Palivoda Vasilii Romanovich , Khanipov Ilmir Failovich
Published: September 2020

The prevailing economic situation warrants oil production emerging realities. Increased producibility and efficiency are promising ways of oil industry developing for now. That's why the advanced use of digital technology in the oil industry is one of the priorities today. Digital technology adoption helps to reduce costs by improving existing workflows, and also provides the capability over the longer term to achieve high levels of economic efficiency in the hard-to-recover reserves development.

The study presents key principles for geological and technical measures (GTM) efficiency improving based on machine learning using an accumulated data of previous work statistical data. The study also demonstrates a method based on the results obtained that allows modifying the existing methodology for developing reserves and involving reserves that are unprofitable today.

The use of machine learning has been examined from a different approaches point of view, such as linear regression and decision tree. The convergence of actual and predicted data was more than 80%, based on a test sample.

The proposed methods and workflows are only the first steps in the technology development to improve the next-generation GTM efficiency. Automatic recruiting helps to improve workflows and optimize productivity. That's why the company doesn't go beyond its initial costs, and can also use reserves that are unprofitable today by changing the investment projects setup methodology.
Reservoir Simulation of Polymer Flooding: Challenges and Current Results
Authors: Sabirov Denis Galievich , Demenev Roman Aleksandrovich , Isakov Kirill Dmitrievich , Ilyasov Ilnur Rustamovich , Orlov Alexander Gennadievich , Glushchenko Nikolay Aleksandrovich
Published: September 2020

Most of the Russian oil fields consist of the complex reservoirs and it is required to apply secondary reservoir development methods, such as waterflooding, in order to increase reservoir development efficiency. However, for highly heterogeneous reservoir with viscous oil, "classical" waterflooding is not enough and there is a need to use enhanced oil recovery methods, one of which is polymer flooding. The prospects polymer solutions injection have been proved in different fields worldwide, including the East-Messoyakhskoye field at the PK1-3 reservoir with high-viscosity oil. At this field, polymer flooding pilots were carried out and taking into account the obtained field data, the geological and dynamic model were updated, which helped to improve the process physics understanding and evaluate the possibility of sweep efficiency increase during project implementation.

This paper describes the challenges, difficulties, applied approaches, results and experience obtained in reservoir simulation of polymer flooding.
Thermo-Tectonic Evolution and Numerical Petroleum System Modeling of One of the Oil Fields on Krasnoleninsky Arch, SW West Siberian Basin
Authors: Röth Joschka , Karpov Yury Alexeevich , Kalmykov Anton Georgievich , Beseleva Ekaterina Viktorovna , Littke Ralf , Kalmykov Georgy Alexandrovich
Published: September 2020

In the West Siberian Basin, thermal maturity anomalies correlate with heterogeneities in the basement and are presumably caused by localized hydrothermal activity. NE and SE oriented faults potentially served as vents for hydrothermal fluids and provided migration pathways for large oil fields. An example oil field located upon the Krasnoleninsky Arch in the southwestern West Siberian Basin was investigated to understand the timing and interplay of the petroleum system elements including the activity of faults.

Three boreholes and two seismic sections were used to build 1D and 2D petroleum system models. Detailed boundary conditions were defined and thermal modeling was performed by matching calculated values to calibration data. Different scenarios of opened/closed faults were tested to determine the history of oil migration. Good calibration with basal heat flow was achieved from initially 95 mW/m2 in the Triassic and slowly decreasing to values between 60 and 70 mW/m2 until today. Modelled present-day surface heat flow varies between 70 and 78 mW/m2. While subsidence is rather continuous from the Early Cretaceous until the Late Eocene, the Lower Cretaceous stands out. This dynamic epoch exhibits fluctuating sedimentation rates and tectonic uplift, which resulted in surface exposure and in local erosional unconformities. NE and SE directed basement lineaments were reactivated mainly as strike-slip faults during the Barremian and the Aptian.

Late Jurassic oil-prone source rocks reached depths between 2,300 and 2,500 m and maximum temperature of 120 to 130 °C. Ro varies around 0.9 % and transformation ratios yield 55 to 75 %. Two peaks of petroleum generation were identified during the Barremian (ca. 120 Ma) and the Campanian (ca. 80 Ma). Since about 600 m of low-permeable rock separate the source rocks and the overlying reservoir rocks, we conclude that both pulses required open faults for successful migration and charge of our example oil field.
Determination of Stress Directions From the Scale of the Volga-Ural Region to the Local Scale of the Field in the Orenburg Region For Optimize the Development System
Authors: Korolkova Kseniy Petrovna , Nikiforova Anna Aleksandrovna
Published: September 2020

Study of changes of regional horizontal stress in the Orenburg region in order to optimize the development of Volga-Ural region oil fields has not been carried out before.

The research is aimed at obtaining the results of the connection between direct (azimuthal electric micro-lateral logging) and indirect (work wells, hydraulic fracturing, tracer studies) methods to determine the direction of maximum stress in a vast territory of two regions: Samara and Orenburg.

A regional map based on the systematized measurements of the azimuthal electric microimager was constructed. This map does not contradict the tectonic and geological concepts of the Devonian system formation, which is the main largest reserve for the Volga-Ural region fields.

A local analysis of the direct and indirect methods relationship to determine the direction of maximum stress at the level of two fields of the Pervomaisky group - G1 and RK1 was conducted. This analysis was performed due to the large amount of input information from indirect data and in order to confirm the distribution of values in the peripheral zone of the regional map, where the reliability of mapping is reduced.

As a result of localization, a relationship was revealed, which allowed us to scale the analysis methodology to the existing fields of Volga-Ural region and to increase the number of indirect studies (tracer studies), as a cheaper analogue to azimuthal electric microblock logging.

Positive conclusions on the interconnection of methods made it possible to optimize the development of a perspective area in the eastern part of the RK1 field with the recommended reorientation of the direction horizontal wellbores with the subsequent economic effect for the company.
Complex Phase Behavior Study of a Near-Critical Gas Condensate Fluid in a Tight HPHT Reservoir
Authors: Yazkov Aleksandr Viktorovich , Gorobets Vyacheslav Evgen'evich , Surkov Evgeniy Viktorovich , Solovyev Vladimir Vladimirovich , Devyatov Andrey Sergeevich , Vokuev Vladimir Sergeevich , Filippova Yulia Aleksandrovna , Ibadullaev PervizGilal ogly , Indrupskiy Ilya Mikhailovich , Lobanova Olga Andreevna , Yushchenko Taras Sergeevich , Cherneva Nadezhda Yurevna , Alekseeva Yulia Vladimirovna
Published: September 2020

The near-critical initial state of the formation fluid with a unique content of C5+ components in a tight reservoir with high temperature and abnormally high reservoir pressure (AHRP) causes significant difficulties in collecting samples of the formation fluid and assessing their adequacy to the actual reservoir mixture both in composition and identified phase state (gas condensate or oil) and phase behavior.

The paper presents the result of the work of the project multidisciplinary team, which includes specialists from the PJSC «NOVATEK» group of companies and the leading Russian Institute of Oil and Gas Problems (OGRI RAS), of studying the near-critical gas condensate system in a HPHT tightreservoir. The effect of well completion and sampling conditions on the composition, phase state and phase behavior of fluid samples is shown. The influence of formation water and residual liquid hydrocarbons (HC), capillary effects, adsorption, and the specifics of the PVT-model tuning on the dew point pressure, the condensate lossdynamics, and the variation of composition and phase state of the fluid with depth is assessed. The results made it possible to clarify the understanding of the reservoir system,develop a program for further research, and improve the history matching of the flow model.

The performed modeling of various factors in a porous medium for the conditions of the studied reservoir showed that the presence of formation water and capillary effects do not noticeably affect the phase behavior of the fluid, but the possible presence of scattered hydrocarbons and the adsorption / desorption of hydrocarbon components can lead to considerable changes in the dew point pressure and the condensate loss dynamics. The significant influence of the PVT model tuning on the calculated distribution of the initial fluid composition over the reservoir volume is demonstrated, including the position of the gas-oil contact and its type (classical gas-liquid contact or supercritical transition to the liquid state).
Geologically Driven Stochastic Inversion of Seismic Data for Reservoir Characterization in Tyumen Formation
Authors: Pirogova Anastasia Sergeenva , Epov Kirill Alexandrovich
Published: September 2020

Under conditions of the Krasnoleninsky field (hydrocarbon producing territory in Western Siberia), the pay zones of the Tyumen formation are characterized by a thin-layered structure and a high degree of spatial variability of petrophysical and lithological characteristics. Due to the low elastic contrasts of reservoir rocks relative to the embedding sand-clay sediments, their prediction from seismic data is challenging. Additional complications are associated with the presence of a significant amount of coal material in the geological section. Minimizing the uncertainties of the pay zones prediction can be achieved by integration a priori geological information, seismic and well logging data. Geological information includes knowledge on depositional conditions and evolution of the sedimentary basin that manifests in vertical and lateral facies successions and trends. The paper presents results of geologically driven stochastic inversion of 3D seismic reflection data at one block of the Krasnoleninsky fields. The proposed approach is based on the parameterization of the available geological information and its integration with the results of the petrophysical interpretation of the well logging data within the framework of stochastic inversion.
Identification of SAP Sources in Offshore Production Wells in the North Caspian Oilfields
Authors: Shtun Sergei , Senkov Alexander , Abramenko Oleg , Rakitin Mickhail , Nagimov Vener , Trusov Alexander , Sviridov Alexander
Published: September 2020

The well integrity monitoring including Sustained Annulus Pressure (SAP) assessment on offshore stationary platforms in the conditions of a limited number of well slots plays an important role in the development of oilfield with thin oil rims and a massive gas cap. The presence of SAP leads to uncontrolled release of gas or liquid to the surface, disruption the operating condition of the wells and its completion components, that overall can result to severe accidents at the offshore oil and gas production facility. Another difficulty that SAP brings is secondary gas cap accumulation across untargeted reservoir zones that might lead to blowouts in operating wells. To identify the causes of SAP, constant monitoring of annulus pressure, as well as proper diagnostics are needed. One of the most reliable and effective methods for identifying SAP causes is Through-Barrier Diagnostics that able to accurately localize reservoir-sources of SAP behind multiple casing strings in the wells, which helps production engineers further production strategy and weighted workover planning. Conventional diagnostics on identifying SAP sources is significantly limited by complexity of the well construction and downhole equipment. This paper describes using of Through-Barrier Diagnostics on the sources of SAP identification on the ice-resistant stationary platform named after Yuri Korchagin, detailly explains the approach and challenges on real case studies. High precision temperature and passive spectral acoustics play a key role in described technique. Passive spectral acoustics, which have a scanning radius of about a few meters, helps to detect fluid flows in the reservoir and behind casing channels in cracked cement.
Multistage Hydrocarbon-Based Fracturing in Tight Gas Formation
Authors: Astafyev Vladimir , Lushev Mikhail , Mitin Alexey , Plotnikov Alexey , Mironov Evgenii , Legay Alexey , Dubnitskiy Ivan , Zavialov Sergei , Vorobyev Vladislav , Mazhirin Yury , Zolnikov Denis
Published: September 2020

In fields where conventional production methods are applied to effectively recover hydrocarbons, well stimulation is a method to obtain additional production or to increase it at later stages of development. Therefore, well stimulation methods and technologies may be improved during field development after evaluating their influence on hydrocarbon recovery. In the case of hard-to-recover reserves for which economically feasible production requires application of well stimulation methods, these technologies should be designed to the maximum extent in the initial stages of field development and subjected to minor adjustments in future. This paper reviews the approach to screening horizontal well completion and stimulation technologies in low-temperature and low-permeable gas reservoirs with minor formation overpressure. It also describes trial application of oil-based frac technology in a vertical pilot well and its adaptation to multi-zone horizontal well conditions.
Results of Implementing An Integrated Approach to Modeling, Planning and Conducting of Hydraulic Fracturing on Bazhenov Shale
Authors: Korobitsyn Dmitri Andreevich , Yanaev Aleksey Mirzoevich , Bochkarev Alexander Vladimirovich , Erofeev Artem Alexandrovich , Prodan Artem Sergeevich , Bukov Oleg Vladimirovich , Migunov Nikolay Mihaylovich , Milkov Alexander Yurievich
Published: September 2020

During the Bazhenov shale development, a new integrated approach to planning the multistage hydraulic fracturing was developed. This approach is applied to each drilled well,thus implementing the strategy of technological experiment, where the well serves as a separate testing ground for testing the developed methods and implementing new technologies.With the help of modern multistage hydraulic fracturing modeling tools, developed jointly with technological partners for the project tasks, a technological experiment plan is drawn up for the well and contains new,potentially effective solutions, as well as the already accumulated experience. In accordance with the developed plan,the multistage hydraulic fracturing operation is modeled, taking into account the geological and geomechanical features of the object, such as lateral and zonal heterogeneity and the existing natural fracture zones.

Using the developed approach, multistage hydraulic fracturing operations were performed on more than 25 wells drilled at the Bazhenov shale, which is equivalent to 450 well operations.During this time, various technological solutions have been developed, tested and implemented,which include the use of new hydraulic fracturing fluid samples, the selection of optimal well perforating scheme,the use of combined proppant packs and hydraulic fracturing using mainly low-viscosity fluids.Active use of specialized software for modeling the hydraulic fracturing process and close cooperation of software developers with hydraulic fracturing engineers has led to the expansion of the functionality of the developed software product, improving its quality, convenience and stability of operation. According to the initial assessment,the implementation of the technological experiment strategy in conjunction with the use of specialized software led to a reduction in drilling hazard mitigation during multistage hydraulic fracturing operations,as well as to an increase in accumulated oil production by an average of 37 %.A database of knowledge and individual,successful technological solutions available for use in similar projects has been created.

Due to the Bazhenov shale unique structure and properties,it was necessary to adapt existing solutions in the industry for conducting multistage hydraulic fracturing in ultra-low layer permeability.The process of searching and creating new technologies, tools for modeling the multistage hydraulic fracturing process and analyzing the results was also successfully initiated. The developed approaches have already shown their effectiveness, and the work results can be replicated on subsequent wells, as well as on similar objects.
Alternative Fracturing Fluids: Expanding the Field of Possible Applications and Properties of Hydrophobically Modified Polyacrylamide
Authors: Aleshina Anna Leonidovna , Shibaev Andrey Vladimirovich , Philippova Olga Evgenievna , Osiptsov Andrei Alexandrovich , Shel Egor Vladimirovich , Paderin Grigory Vladimirovich , Saifutdinov Elnar Faridovich , Churakov Artem Vladimirovich , Fayzullin Ildar Gayazovich
Published: September 2020

In this paper, the properties of an alternative fluid for hydraulic fracturing (HF) technology based on hydrophobically modified polyacrylamide (HM-PAAm) are studied. HM-PAAm forms gels as a result of cross-linking of polymer chains by hydrophobic domains. Such cross-links are strong enough to impart resistance to temperature, but they can break and recombine under external influences, which makes it possible to restore properties after strong mechanical shear stresses. In the work, the influence of polymer concentration, temperature, and shear rate on the rheological properties of the gels was studied and the conditions for producing gels promising for use in hydraulic fracturing technology were determined.
Features of Killing Wells Operating Fractured Formations with Abnormally Low Formation Pressures and High Gas Factor
Authors: Shaydullin Vadim Aleksandrovich , Vakhrushev Sergey Aleksandrovich , Magzumov Niyaz Rinatovich , Yanson Sergey Olegovich , Akhmerov Ilgam Anvarovich
Published: September 2020

The article describes the development of a technology meant to kill wells in fractured carbonate reservoirs of the Republic of Bashkortostan with abnormally low reservoir pressure (ALRP) and high gas-oil ratio. Initially, various technologies were tested in wells to solve this problem: invert emulsion muds, biopolymer solutions, crosslinked gels and water-swellable polymers. However, they demonstrated low efficiency. A new killing technology based on a foam-gel system was selected and adapted to the existing conditions to enhance killing efficiency in complicated geological conditions. Successful tests were performed in three wells of reef fields with ALRP.
Persistent domestic circulation of African swine fever virus in Tanzania, 2015-2017
Authors: Yona Clara M. , Vanhee Merijn , Simulundu Edgar , Makange Mariam , Nauwynck Hans , Misinzo Gerald
Published: September 2020

Background: African swine fever (ASF) is a highly fatal viral hemorrhagic disease of domestic pigs that threatens livelihoods and food security. In Africa, ASF virus (ASFV) circulates in sylvatic (transmission between warthogs and soft argasid ticks) and domestic (transmission between domestic pigs) cycles, with outbreaks resulting from ASFV spill-over from sylvatic cycle. A number of outbreaks were reported in different parts of Tanzania between 2015 and 2017. The present study investigated ASFV transmission patterns through viral DNA sequencing and phylogenetic analysis. A total of 3120 tissue samples were collected from 2396 domestic pigs during outbreaks at different locations in Tanzania between 2015 and 2017. Partial sequencing of the B646L (p72) gene was conducted for diagnostic confirmation and molecular characterization of ASFV. Phylogenetic analysis to study the relatedness of current ASFV with those that caused previous outbreaks in Tanzania and representatives of all known 24 ASFV was performed using the Maximum Composite Likelihood model with 1000 bootstrap replications in MEGA 6.0. Results: ASFV was confirmed to cause disease in sampled domestic pigs. ASFV genotypes II, IX, and X were detected from reported outbreaks in 2015-2017. The current ASFV isolates were similar to those recently documented in the previous studies in Tanzania. The similarities of these isolates suggests for continuous circulation of ASFV with virus maintenance within the domestic pigs. Conclusions: Genetic analysis confirmed the circulation of ASFV genotypes II, IX, and X by partial B646L (p72) gene sequencing. The similarities of current isolates to previously isolated Tanzanian isolates and pattern of disease spread suggest for continuous circulation of ASF with virus’ maintenance in the domestic pigs. Although certain viral genotypes seem to be geographically restricted into certain zones within Tanzania, genotype II seems to expand its geographical range northwards with the likelihood of spreading to other states of the East African Community. The spread of ASFV is due to breach of quarantine and transportation of infected pigs via major highways. Appropriate control measures including zoosanitary measures and quarantine enforcement are recommended to prevent ASF domestic circulation in Tanzania.
Meta-analysis reveals severe pollen limitation for the flowering plants growing in the East Himalaya-Hengduan Mountains region.
Authors: Jiang Xianfeng , Xie Yanping
Published: September 2020

Background: Pollen limitation occurs widely and has an important effect on flowering plants. The East Himalaya-Hengduan Mountains region is a global biodiversity hotspot. However, to our knowledge, no study has synthetically assessed the degree of pollen limitation in this area. The present study aims to reveal the degree of pollen limitation for the flowering plants growing on East Himalaya-Hengduan Mountains and to test whether the reproductive features or the elevation is closely correlated with the degree of pollen limitation in this area. Results: We complied data from 76 studies, which included 96 species and 108 independent data records. We found that the flowering plants in this area undergo severe pollen limitation (overall Hedges’ d=2.004, with a 95% confidence interval [1.3264, 2.6743]) that is much higher than that of the flowering plants growing in many other regions around the world. The degree of pollen limitation was tested to determine the correlation with the capacity for autonomous self-reproduction and with the pollination pattern (generalized vs. specialized pollination) of plants. In addition, we found a clear relationship between elevation and the degree of pollen limitation, which indicates that plants might undergo more severe pollen limitation in relatively high places.Conclusions: This paper is the first to address the severe pollen limitation of the flowering plants growing in East Himalaya-Hengduan Mountains region. Moreover, we reveal the positive correlation between elevation and the degree of pollen limitation.
The influence of integrated geriatric outpatient clinics on the health care utility of older people
Authors: Wei Yu-Ju , Hsieh Cheng-Fang , Huang Yu-Ting , Huang Ming-Shyan , Fang Tzu-Jung
Published: September 2020

Background: The number of people aged greater than 65 years is growing in many countries. Taiwan will be a superaged society in 2026, and health care utilization will increase considerably. Our study aimed to evaluate the efficacy of the geriatric integrated outpatient clinic model for reducing health care utilization by older people.Methods: This was a retrospective case-control study. Patients aged greater than 65 years seen at the geriatric outpatient clinic (Geri-OPD) and non-geriatric outpatient clinic (non-Geri-OPD) at a single medical centre were age and sex matched. Data on the number of outpatient clinic visits, emergency department visits, hospitalizations and medical expenditures were collected during the first and second years. A subgroup analysis by Charlson comorbidity index (CCI) and older age (age≧80 years) was performed, and the results were compared between the Geri-OPD and non-Geri-OPD groups.Results: A total of 6723 patients were included (3796 women and 2927 men). The mean age was 80.42 ± 6.39 years. There were 1291 (19.2%) patients in the Geri-OPD group and 5432 (80.8%) patients in the non-Geri-OPD group. After one year of regular follow-up, the Geri-OPD patients showed a significant reduction in the types of drugs included in each prescription (5.62±10.85) and the number of clinic visits per year (18.18 ± 48.85) (P<0.01). After a two-year follow-up, the number of clinic visits, emergency department visits, and hospitalizations and the annual medical costs were still decreased in the Geri-OPD patients. The Geri-OPD patients had more comorbidities and a higher rate of health care utilization than the non-Geri-OPD patients. In the subgroup analysis, patients with more comorbidities (CCI≧2) and an older age (≧80 years) in the Geri-OPD group showed a significant reduction in health care utilization. The Geri-OPD patients also showed a significant decrease in medical utilization in the second year compared with the non-Geri-POD patients.Conclusion: The Geri-OPD reduced medical costs, the number of drugs prescribed, and the frequency of outpatient clinic visits, emergency department visits and hospitalizations in older patients with complicated conditions. The effect was even better in the second year.
Identification of bipolar disorder using a combination of multimodality magnetic resonance imaging and machine learning techniques
Authors: Li Hao , Cui Liqian , Cao Liping , Zhang Yizhi , Liu Yueheng , Deng Wenhao , Zhou Wenjin
Published: September 2020

Background: Bipolar disorder (BPD) is a common mood disorder that is often goes misdiagnosed or undiagnosed. Recently, machine learning techniques have been combined with neuroimaging methods to aid in the diagnosis of BPD. However, most studies have focused on the construction of classifiers based on single-modality MRI. Hence, in this study, we aimed to construct a support vector machine (SVM) model using a combination of structural and functional MRI, which could be used to accurately identify patients with BPD.Methods: In total, 44 patients with BPD and 36 healthy controls were enrolled in the study. Clinical evaluation and MRI scans were performed for each subject. Next, image pre-processing, VBM and ReHo analyses were performed. The ReHo values of each subject in the clusters showing significant differences were extracted. Further, LASSO approach was recruited to screen features. Based on selected features, the SVM model was established, and discriminant analysis was performed.Results: After using the two-sample t-test with multiple comparisons, a total of 8 clusters were extracted from the data (VBM = 6; ReHo = 2). Next, we used both VBM and ReHo data to construct the new SVM classifier, which could effectively identify patients with BPD at an accuracy of 87.5% (95%CI: 72.5-95.3%), sensitivity of 86.4% (95%CI: 64.0-96.4%), and specificity of 88.9% (95%CI: 63.9-98.0%) in the test data (p=0.0022). Conclusions: A combination of structural and functional MRI can be of added value in the construction of SVM classifiers to aid in the accurate identification of BPD in the clinic.
FOXM1 modulates docetaxel resistance in prostate cancer by regulating KIF20A
Authors: Yu Hongbo , Xu Zheng , Guo Maomao , Wang Weiwan , Zhang Weican , Liang Sudong , xu zhibin , Ye Jun , zhu gangyi , zhang chenyang , lin jianzhong
Published: September 2020

Background: Docetaxel resistance affects prognosis in advanced prostate cancer (PCa). The precise mechanisms remain unclear. The transcription factor Forkhead box M1 (FOXM1), which participates in cell proliferation and cell cycle progression, has been reported to affect the sensitivity of chemotherapy. This study explores the role of FOXM1 in PCa docetaxel resistance and its association with kinesin family member 20 A (KIF20A), which is known to promote therapeutic resistance in some cancers.Methods: We monitored cell growth using MTT and colony formation assays, and cell apoptosis and cell cycle progression using flow cytometry. Wound-healing and transwell assays were used to detect cell invasion and migration. mRNA and protein expression were analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blotting. We monitored FOXM1 binding to the KIF20A promoter using the ChIP assay. Tumorigenicity in nude mice was used to assess in vivo tumorigenicity.Results: FOXM1 knockdown induced cell apoptosis and G2/M cell cycle arrest, suppressing cell migration and invasion in docetaxel-resistant PCa cell lines (DU145-DR and VCaP-DR). Exogenous FOXM1 overexpression was found in their parental cells. Specific FOXM1 inhibitor thiostrepton significantly weakened docetaxel resistance in vitro and in vivo. We also found FOXM1 and KIF20A exhibited consistent and highly correlated overexpression in PCa cells and tissues. FOXM1 also regulated KIF20A expression at the transcriptional level by acting directly on a Forkhead response element (FHRE) in its promoter. KIF20A overexpression could partially reverse the effect on cell proliferation, cell cycle proteins (cyclinA2, cyclinD1 and cyclinE1) and apoptosis protein (bcl-2 and PARP) of FOXM1 depletion.Conclusions: Our findings indicate highly expressed FOXM1 may help promote docetaxel resistance by inducing KIF20A expression, providing insight into novel chemotherapeutic strategies for combatting PCa docetaxel resistance.
Depletion of GPSM1 enhances ovarian granulosa cell apoptosis via cAMP-PKA-CREB pathway in vitro
Authors: Cai Xuzi , Fu Huijiao , Wang Yan , Liu Qiwen , Wang Xuefeng
Published: September 2020

Background Genetic causes of premature ovarian insufficiency (POI) account for approximately 20~25% of patients. So far, only a few genes have been identified. Results Here, we first identified the c.1840C>A on G-protein signaling modulator 1 (GPSM1) as a susceptibility locus for POI in 10 sporadic POI patients by whole-exome sequencing. The frequency of GPSM1 c.1840C>A was then verified as 3/20 in a POI sample of 20 patients (including the above 10 patients) by Sanger sequencing. RT-PCR and western blot analysis showed the expression of GPSM1 in rat ovaries was increased in the large antral follicle stage compared to the primordial follicle stage (P<0.01). The cell proliferation assay (CCK8) and flow cytometry suggested that the small-interfering RNA-induced silencing of Gpsm1 significantly increased apoptosis and decreased proliferation of rat ovarian granulosa cells (GCs) (P<0.01). Furthermore, suppression of Gpsm1 in GCs reduced levels of cAMP, PKAc, p-CREB as well as the ratio of Bcl-2/Bax, and increased the expression of Caspase-3 and Cleaved Caspase-3 (P<0.01). Conclusions In summary, this study identified a susceptibility variant GPSM1 c.1840C>A of POI for the first time. Gpsm1 was related to rat follicle development, and silencing of Gpsm1 increased apoptosis and decreased proliferation in rat GCs, possibly through inhibition of the cAMP-PKA-CREB pathway.
Influence of a 100-mile Ultramarathon on Heart Rate and Heart Rate Variability
Authors: Paech Christian , Schrieber Simone , Dähnert Ingo , Hellinger Paul Schmidt- , Wolfarth Bernd , Wüstenfeld Jan , Thouet Thomas
Published: September 2020

BACKGROUND: The aim of this study was to investigate the impact of an ultra-marathon (UM) with a distance of 100 miles on heart rate (HR) and heart rate variability (HRV). METHODS: 28 runners (25 males and 3 females) underwent 24-hour Holter ECG monitoring one week before the UM (U1), immediately after (U2) the UM and after a week of recovery (U3). The influence of age, body mass index (BMI), HR and HRV on the run time as well as recovery were investigated. RESULTS: A rise in the baseline heart rate (18.98%) immediately after the run accompanied by a significant drop in the standard deviation of all normal RR intervals (SDNN) (7.12%) one week after. Except for the age of the runners, BMI, HR and HRV showed no influence on the competition time. Full return of HRV to the athletes´ individual baseline did not occur within one week. There were no significant differences between finishers and non-finishers in analysed parameters.CONCLUSION: The present results show that a 100-mile run leads to an increase in sympathetic activity and thus to an increase in heart rate and a decrease in HRV. In addition, HRV might be a suitable parameter to evaluate full recovery after a 100-mile run.
Efficacy of prophylactic methylprednisolone on reducing the risk of post-extubation stridor in an emergency setting: study protocol for a randomized controlled trial
Authors: Wang Jingyi , Walline Joseph Harold , Yin Lu , Dai Yili , Dai Jiayuan , Zhu Huadong , Yu Xuezhong , Xu Jun
Published: September 2020

Background: Post-extubation stridor (PES) is one of common complications of invasive respiratory support, with severe cases leading to extubation failure (need reintubation within 48 hours after extubation) and increased mortality. Previous studies confirmed that prophylactic corticosteroids play an important role in reducing the risk of PES and extubation failure. However, few study the efficacy of corticosteroid on preventing PES in patients with an emergency intubation. Aim: To evaluate whether a single dose of methylprednisolone given over a set time-frame before extubation is effective in preventing PES in patients with an emergency intubation. Methods: A multicenter, randomized, placebo-controlled trial will be performed. The trial will include 242 patients who fail the cuff-leak test (CLT) in the intervention. The patients will be randomly assigned to either intravenous methylprednisolone 40mg or placebo four hours prior to extubation. Other eligible patients who pass the CLT will be included in non-intervention (observation). The primary endpoint is the incidence of PES within 48 hours after extubation, the secondary endpoints are the oxygen therapy, requirement for respiratory support, reintubation secondary to PES, adverse effects within 48 hours after extubation, hospital length of stay and hospital mortality.Discussion: Patients who are intubated on an emergency basis have a higher risk of intubation-related complications due to some inevitable reasons. Earlier studies showed more than 10 different corticosteroids treatments on PES prevention, while only a simple and effective treatment will be appropriate for Emergency Department therapy. Additionally, corticosteroids administration is usually companied by adverse effects, thus the recording of adverse effects is important for further pros and cons analysis of prophylactic corticosteroid use among emergency patients. Trial registration: Chictr.org.cn, ChiCTR2000030349. Registered on 29 Feb 2020.
Evaluation of acute central serous chorioretinopathy using enhanced depth imaging OCT and multifocal electroretinography
Authors: Hong In Hwan , Chang In Boem , Jeon Gang Seok , Han Jae Ryong
Published: September 2020

Background: To evaluate functional and structural abnormalities in patients with acute central serous chorioretinopathy (CSC) with multifocal electroretinography (mfERG) and enhanced depth imaging optical coherence tomography (EDI-OCT)Methods: This prospective observational study included 57 patients with unilateral CSC. Both eyes underwent mfERG and EDI-OCT. Peak amplitudes and implicit times of the ﬁrst kernel responses were analyzed and compared with those in 25 age-matched normal controls. Correlational analyses were performed between the mfERG results and EDI-OCT parameters. The thicknesses of the central retina, subretinal fluid, and choroid was measured at baseline and 3 months later.Results: Compared with the normal controls, the amplitude and implicit time on mfERG were significantly impaired in the area with serous retinal detachment (SRD). The P1 amplitude and implicit time of the areas beyond the SRD were also found to be significantly impaired in the affected eyes. Eyes with a greater reduction in SRD had a less impaired mfERG response in fellow eyes than those whose retinal detachments were not spontaneously decreased by more than 90% after 3 months. Correlational analysis did not reveal any significant correlations between mfERG values and OCT parameters except for central choroidal thickness. The subfoveal choroidal thickness was negatively correlated with the mfERG parameters.Conclusions: The findings of this study indicate diffuse functional impairment in acute CSC involving both eyes and areas beyond the SRD. The retinal response of the unaffected eye was associated with regression of SRD. Functional retinal abnormality was found to correlate with pathological changes in the choroid.