bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast estimation method of renewable energy carrying capacity of power grid based on nadir frequency constraint
Authors: Jiang Xiaoliang , Xie Yan , Si Ruihua , Tang Xiaojun , Yu Linlin , Li Jing
Published: June 2021

With more and more renewable energy connected to the power system, the power system gradually presents the characteristics of low inertia and the risk of frequency instability gradually becomes prominent. Therefore, nadir frequency has become one of the limiting factors of renewable energy carrying capacity. In this paper, firstly, based on the swing equation, frequency dynamic response after power loss was analysed. Secondly, quantitative analysis on system inertia time with renewable resources was carried out, with higher penetration rate k and the replacement rate a, the inertia time is relative lower. Thirdly, fast estimation method of renewable energy carrying capacity of power grid based on nadir frequency constraint was proposed. Finally, taking a regional power grid as an example, the effectiveness of the proposed estimation method is verified.
Construction of evaluation index system of reclaimed water development and utilization potential based on AHP
Authors: Wu Leixiang , Li Ang , Guan Ronghao , Wang Zhuowei , Liu Xingchen
Published: June 2021

The shortage of water resources has severely restricted the rapid development of modern cities in China, and the recycling of reclaimed water is one of the important methods to effectively solve the bottleneck problem of urban water shortages. Based on the Analytic Hierarchy Process (AHP), this study determines the evaluation indexes and their weights from social and technical levels respectively and constructs an evaluation index system of reclaimed water development and utilization potential, which contains 3 levels, 5 criteria and 19 alternatives, focusing on the production, utilization and benefit of reclaimed water and other characteristic indexes. From the weighting results of the index system, among the main influencing factors of reclaimed water development and utilization, the water quantity factor has the greatest influence, the influence of water usage and water quality assurance ranks second, and the economic factor has the least influence. This evaluation system provides a useful reference for the reasonable development and utilization of regional reclaimed water in the future.
Research and Design of Automatic Chip Removal Model Based on Cutting Machine
Authors: Lu Yaping
Published: June 2021

Aiming at the widespread environmental pollution problem of cutting machine tools, an automatic chip removal model platform is designed based on solid works. The model platform has the functions of automatic collection of waste chips and automatic chip removal through the air guide groove. A new type of cutting seam is designed to prevent the scraps from being taken out by the cutter, and remove the scraps adhered on the cutter due to high temperature. The inner loop gas path is designed, which is composed of two air inlets and 180 degree evenly distributed air outlets, forming a unique annular gas path. The gas path relies on the annular gas path, which blows away the waste chips during the cutting work of the machine tool, and enters the inner cavity of the machine tool through the new cutting seam. The automatic chip removal model platform is based on the chip removal of the machine tool itself, which can improve the chip removal efficiency of the waste and reduce the scratches on the surface of the material.
Competitiveness evaluation and cluster analysis of logistics industry in Henan Province based on SPSS 22.0
Authors: Liu Qianqian
Published: June 2021

The logistics industry is an important support for the construction and development of my country’s national economy, and there is a close relationship between regional logistics and regional economy. In order to comprehensively evaluate the level of logistics competitiveness in Henan Province, this paper has established 11 evaluation indexes of Henan logistics industry competitiveness from three perspectives: regional economic conditions, logistics demand and logistics industry support factors. With the help of SPSS 22.0 software for factor analysis, 11 indexes are divided into two public factors: logistics economic development environment, logistics demand and scale, and the competitiveness of the logistics industry of 18 province-administered cities in Henan Province is ranked. According to the scores of 2 factors, the 18 provincial cities were divided into five categories using the systematic cluster analysis method, and then the development ideas for the development of the logistics industry of each type of provincial cities were put forward to provide a reference for the overall development of the logistics industry in Henan Province. At the same time, it also provides reference for the development of logistics industry in other regions.
Intelligent monitoring system of elevator Internet of things
Authors: An Ziliang , Liu Shaofeng , Bai Dingsong , Wang Ning , Yu Xintong
Published: June 2021

The function of traditional elevator monitoring system is relatively simple. It cannot realize on-demand maintenance and fault warning. To solve such problems, this paper builds an intelligent monitoring system of elevator Internet of Things based on multi-sensor information fusion, bus communication and probability and statistical analysis technology. Managers can access the control platform through smart terminals or web browsers to achieve data query, video monitoring, alarm management of the elevator system, health management and other functions, which can help managers detect hidden dangers of elevator safety in time and ensure safe and efficient operation of elevators.
The Influence of Temperature on the Secondary Use of Lithium Iron Phosphate Power Battery
Authors: Meng Qingbiao , An Ziliang , Yu Xintong , Wang Ning , Bai Dingsong , Liu Shaofeng
Published: June 2021

At different temperatures, we test the charge and discharge performance of lithium iron phosphate power batteries after retirement, and study the effect of temperature on the performance of decommissioned batteries, including the test of capacity and energy, and the battery voltage test. Experimental results show that low temperature will lead to a decrease in charge and discharge capacity and energy, and affect the performance of decommissioned batteries.
Calculation Method of Electric Vehicle Baseline Load Based on Classification
Authors: Zhang Yue , Liu Mingguang , Liu Dunnan , Jia Heping , Su Shu , Peng Xiaofeng , Zou Mengjiao , Shang Shanshan , Yang Ye
Published: June 2021

In the incentive based demand response project, the baseline load calculation of electric vehicle users can provide quantitative basis for evaluating the power demand response and the load adjustment degree of users. The charging load of electric vehicle is different from the traditional electric load, which has greater flexibility and is more affected by user’s behavior. This paper analyzes the characteristics and influencing factors of electric vehicle charging load. On the basis of summarizing the common calculation methods of user baseline load at home and abroad, this paper puts forward the calculation method of electric vehicle baseline load based on classification, and finally analyzes the accuracy and applicability of this method combined with specific examples.
The Research on System of Charging Load Aggregator Participating in Market Transaction based on Internet of Vehicles
Authors: Zhang Yue , Yang Jing , Li Jun , Han Yingzhu , Zhao Zhiqiang , Du Xin , Liu Mingguang , Liu Dunnan
Published: June 2021

The electric vehicle market has gained rapid growth in various countries. Electric vehicles will be one of the largest loads in the future power grid. This paper sorts out the typical models of charging load aggregators’ participation in ancillary services, demand response, and valley drop electricity curve tracing, and formulates the trading strategies of charging load aggregators in the electricity direct trading market, ancillary service market and electricity derivatives market. And then the strategy of aggregators participating in multi market coordination is proposed. Based on the contribution of aggregators to participate in market transactions, considering the willingness of different entities to participate in charging load aggregated transactions, a reasonable game model as well as a fair and reasonable value sharing mechanism is established to achieve the transmission of market trading dividends and promote the charging load aggregators to participate in the electricity market transactions.
Dynamic response and failure mode of series isolation system under explosion load
Authors: Yanan Wang , Bin Peng , Anan Liu , Yonghui Liu
Published: June 2021

The numerical model of the series isolation structure was established by using the finite element software to simulate the dynamic behavior of the series isolation structure after explosions occurred at different positions, and study the dynamic response and failure mode of the series isolation structure under explosion load. The results show that the vertical displacement and speed of the beams on each floor show a certain regularity with the passage of time. When columns at different positions encounter explosive loads, they will cause local collapse and damage of the structure, and the damage is mainly distributed in the longitudinal and transverse ranges where the columns are located. Compared with the inner column, the structural damage caused by the explosion load on the corner column and side column is more serious.
Parameter optimization analysis of fuel injection system for high pressure common rail diesel engine
Authors: Xuejun Wang , Fangjian Xu , Yiran Wang
Published: June 2021

The cleaning and energy-saving environmentally friendly diesel engine, with the high pressure common rail fuel injection system, is the main driving force in the transportation sector. Being the core and key technology, the high pressure common rail fuel injection system is the inevitable developing trend of the future fuel injection system. The parameter optimization design of the high pressure common rail fuel injection system is of great practical significance to improve. the operation stability of common rail system. By up-grading the fuel control precision and optimizing the overall performance of the engine, the purpose of energy saving and emission reduction can be finally achieved.
Analysis and Application of Optimal and Fast Drilling Technology in Gaoshangpu Block of Jidong Oilfield
Authors: Li Wen , Zhao Dawei , Tao Fu , Lv Zhuolin , Li Ning , Zhao Xianlong
Published: June 2021

The Gaoshangpu block of Jidong Oilfield is a hot block for increasing production and storage in Jidong Oilfield. High-quality and efficient drilling and completion can shorten the operation time and have huge economic and social benefits. Aiming at the problems of large well depth, complex geological conditions, poor stratum drillability, low drilling machinery efficiency, and long drilling cycle in the Gaoshangpu block of Jidong Oilfield, this paper optimizes its drill bits, speed-up tools, drilling parameters, and drilling fluid performance. Through bit optimization, a PDC bit optimization template is formed. A single S1942 PDC and BTM159AR PDC bit can solve the problem of poor formation drillability, improve drilling efficiency, shorten completion time and optimize speed-up tools in the study area. For glutenite developed stratum (bottom of Guantao Formation), we use shock-absorbing thruster, and for gray mudstone (Shahejie Formation), we use shock-absorbing thruster + curved screw. 1% organic silicon polymer can be added to the three-open drilling fluid to improve the drilling fluid performance. The adding of the compound (PLH: KPAM: ammonium salt = 1: 1: 2) can inhibit mud making, and the 2% anti-collapse agent before drilling into basalt can solve the well wall collapse of Shahejie Formation and Guantao Formation. The liquid with density of 1.44-1.45 can prevent well overflow. The research results provide guidance for high-quality and efficient drilling in the Gaoshangpu block of Jidong Oilfield and ensure the safety of drilling operations.
Optimization of customized bus green line network based on passenger travel time window
Authors: Lang Guoling
Published: June 2021

In order to solve the problem of public transportation in China, this paper optimizes the customized bus network based on the passenger travel time window and the operating cost. Firstly, the passenger travel time window is proposed, and then a model about the minimum objective of customized bus operation cost, environmental protection cost and passenger travel cost is established, which is solved by lingo software, and then the customized bus route planning is studied according to the case, and finally the conclusion of this paper is drawn.
Calibration method research and uncertainty evaluation of End-tidal carbon dioxide concentration of Multifunction Patient Monitoring Instruments
Authors: Li Weiwei , Jiang Junjie , Li Hongliang , Liu Mengjun
Published: June 2021

The monitoring of end-tidal carbon dioxide concentration has the characteristics of non-invasive and quick response, which has become one of the important ways of clinical vital signs monitoring. This monitoring equipment is widely used in emergency operating room, critical care and other important departments. The calibration of end-tidal carbon dioxide concentration can effectively test the accuracy and safety of equipment, and the research of calibration method and the evaluation of uncertainty are of great significance.
Research on Low Carbon Multimodal Transport Network Structure and Rapid Transit Mode
Authors: minai He , Tian Xia , yujing lai
Published: June 2021

Practice at home and abroad has proved that multimodal transport is a safe, efficient, low-carbon and environmental protection advanced transport organization. In recent years, the Chinese government has introduced a series of policy measures, to encourage broad nationwide transport and multimodal transport. This paper draws on the advanced experience of Europe, america and other developed countries, construction of a network structure model. In this paper, four typical transport modes of container unit cargo by rail are described, and the layout design of each mode loading and unloading operation area is carried out.
Analysis on the hazard control technology of volatile organic compounds
Authors: Liu Chunhui , Gao Jucheng
Published: June 2021

This paper introduces the Constitution and mechanism of VOCs, and then analyzes the hazard path, demonstrates the importance of VOCs treatment, analyzes the status quo of VOCs treatment, and introduces in detail various methods of controlling VOCs Pollution, such as combustion, absorption (washing), condensation, charging and biological methods, It is easy to use for reference on the treatment methods of VOCs, and to reduce the harm.
Research on carbon emission reduction calculation and user subsidy mechanism of electric vehicles
Authors: Zou Mengjiao , Liu Mingguang , Liu Dunnan , Jia Heping , Su Shu , Peng Xiaofeng , Zhang Yue , Shang Shanshan
Published: June 2021

Under the goal of carbon neutralization and carbon peak, China’s electric vehicle industry will usher in a high-speed development stage. Electric vehicles can achieve carbon emission reduction from two aspects of electric energy substitution and clean energy substitution. In this paper, the carbon emission reduction benchmark of electric vehicles is determined, and the Bass model is used to predict the number of electric vehicles. On this basis, the carbon dioxide emissions reduced when electric vehicles replace fuel vehicles to meet the travel requirements and the carbon dioxide emissions of electric vehicles with different proportions of renewable energy generation are analyzed. Finally, the benefits of carbon emission reduction under decentralized and centralized modes are studied to determine the subsidy range of electric vehicle users.
Optimization of enzymatic hydrolysis assisted ultrasonic extraction of polyphenols from Chaenomeles sinensis (Thouin) koehne
Authors: Fang Shuangjie , Hu Fuxia , Li You , Wang Fengqin , Zhou Changxin , Wang Zhaosheng
Published: June 2021

In this paper, the optimal extraction process of polyphenols from Chaenomeles sinensis (Thouin) koehne was studied by single factor test and response surface test. Research results showed that the optimum extraction conditions were as follows: enzymatic time 55 min, ethanol concentration 59%, enzymatic liquid-material ratio 28:1 mL/g, pectinase amount 20 μL/g, enzymatic pH 3.4, enzymatic temperature 65°C, ultrasonic liquid-material ratio 30:1 mL/g, ultrasonic time 40 min, ultrasonic temperature 55°C. Under these conditions, the extracted content of Chaenomeles sinensis (Thouin) koehne polyphenols was 62.07 mg/g.
Study on The Relationship between Vegetation Index And Bird Diversity in Beidagang Wetland
Authors: Zi-ling Dai , Meng-xuan He , Dan-ran Lv , Jia-rui Liu , Ling-xuan Xu , Peng-cheng Wan , Xun-qiang Mo
Published: June 2021

Birds are an important part of wetland ecosystem. With the development of urbanization, bird vegetation is destroyed seriously, threatening bird diversity. In view of this, this paper studied the dynamic changes of NDVI (Normalized Difference Vegetation Index) and three bird diversity indexes (Shannon-Wiener index, Simpson index, Pielou index), and explored the relationship between the two, based on the wetland bird survey data and Landsat 8 remote sensing images from 2015 to 2019 in Beidagang Wetland. The results showed that: Although the growth condition of wetland plants changed from poor to better due to the ecological water rehydration measures adopted in the later period, the three indexes leveled off except in 2018. Spearman correlation analysis showed that Shannon-Wiener index was highly negatively correlated with NDVI, and slightly negatively correlated with Simpson index and Pielou index, indicating that NDVI in Beidagang Wetland had much less impact on bird diversity than other habitat factors, and could not play a leading role.
Microzonation of Ground Motion Parameters in Shangluo City
Authors: Zhang Hanliang , Li Baolai , Wang Xiaojun , Nie Dawei , Li Chunfeng
Published: June 2021

This paper studied the regional seismic tectonic characteristics, regional seismic activity characteristics, the near-field seismic tectonic characteristics, near-field earthquake activity characteristics about the site of Seismic Microzonation in Shangluo City, seismic belts and potential seismic source zone were divided, calculating the seismic risk analysis of the bedrock of the site, surveying engineering geological conditions in the site, carrying out the seismic response analysis of the site, and zoning the ground motion parameters of the site. The above results provide a basis for the seismic fortification of the proposed general engineering in the site.
5G Technology and Its Application in the Seismograph Intelligence
Authors: Lin Duibo
Published: June 2021

In order to meet the national intelligent development needs of coal mines, construct smart mines, improve their safety production levels and finally realize the vision of flexible manpower line and unmanned development, the application of 5G communication technology in intelligent seismographs for underground coal mines was discussed in this study based on the development history and advantages of 5G technology. Next, the application of 5G technology in the intelligent development of coal mines and the main application scenarios were explored by combining its three major unique advantages: high speed, low time delay and wide connection. The emphasis was laid on studying the seismograph intelligence based on 5G module, and then the uplink and downlink rates of three major operators under the same environmental conditions as well as uplink and downlink rates of the same operator at different positions under the 5G environment were tested. After being connected to 5G module, the seismographs sent data to the server side with fixed IP address, it was verified through the test that the normal communication was enabled under both TCP and UDP forms, and on this basis, the functions of seismograph, namely data passthrough to server and wireless real-time data transmission, were realized.
Research on Functional Interdependence Patterns of “Village-Urban” Spatial Structure of Shenzhen: A Living and Activity Space Perspective
Authors: Li Yang , Song Jusheng
Published: June 2021

The urban village is a special product of the rapid urbanization process in China. To accurately understand its functional embedding mode in the urban organism is an important decision-making prerequisite for optimizing the governance effectiveness of urban renewal. Taking residents’ living and activity space as the breakthrough point, this paper analyzes the spatial functional patterns of villages in cities by measuring the “village-urban” interdependence relationship based on cellphone big data. It is founded that urban villages in Shenzhen are closely related to other parts of the city, and are not self-isolated communities. At the same time, due to the extensive construction and management mode, the function homogenization of urban village space is obvious, and its location is the main determinant of its participating way in urban activities. The research holds that from the perspective of providing citizens with low-cost opportunity to participate in urban public life and ensuring the resilient development capacity, it is necessary to coordinate and reserve a certain proportion of urban village residential land within the sub-community of residents’ living and activity space to promote the benign and healthy development of urban space organisms.
Scheme Design of Returnable Transportation Packaging System between Shandong Province and South Korea
Authors: Wang Jun , Hou Yimeng , Wang Weishan
Published: June 2021

The main trade product categories and logistic packaging standard systems were firstly investigated between Shandong province and South Korea. Based on the results, the auto parts were chosen as the target product to design the returnable transportation packaging system. Therefore, the system composed of standardized plastic pallet, nested plastic returnable box and top cover were designed for the light auto parts, while the folding visualized metal mesh box was designed for the heavy auto parts. By simulating the adaptability among different specifications of packaging equipment and the shipping containers, the recycling plastic pallet with size of 1140 mm×980 mm, plastic packaging boxes with size of 480 mm×380 mm were preferred to match 40 ft containers, the plane and space loading efficiencies of which are 94.89% and 87.35%, respectively. While, the metal mesh boxes with 1000 mm×800 mm×760 mm were preferred to match with 20 ft containers, with the plane and space loading efficiencies of 94.89% and 87.35%, respectively.
Research on Climate Adaptation Design Strategy Driven by Spatial Performance from the Perspective of Land-Based Rationalism: Taking the Academic Complex Project in Central School of Communist Youth League of China as an Example
Authors: Xu Bin , Xiang Yuan , Li Dongzhe
Published: June 2021

With the rapid urban development, the construction of public buildings in China has been greatly promoted, and the problem of large energy consumption of public buildings has also become increasingly prominent, with a stronger demand for close combination of public buildings and passive design. Based on the characteristics of theater space, this paper mainly studies the passive design method of large space, excellently integrates climate adaptability design technology with passive building design strategy, and explores the optimal passive design scheme for theater buildings, by taking the academic complex project in Central School of Communist Youth League of China as an example, with passive priority and active optimization for the principle from the aspects of climate adaptation and indoor environment comfort.
Analysis of Traffic Flow Characteristics in Intelligent Networking Environment
Authors: Liu Pengqun
Published: June 2021

In an intelligent networked environment, both the car and the road are more intelligent, and the information interaction between the vehicle and the roadside equipment is more frequent, the vehicle has a greater advantage in information acquisition, processing, decision-making and standardized driving compared to ordinary manual driving vehicles. The study of mixed traffic flow between intelligent networked vehicles and ordinary vehicles in the intelligent networked environment is of great significance to improve the operational efficiency of traffic flow and road capacity. In this paper, we build simulation scenarios in Vissim based on the meta cellular automaton traffic flow model and the Wiedemann model, conduct simulation experiments on the mixed traffic flow of intelligent networked vehicles and ordinary vehicles, and study and analyse the influence of the change in the proportion of intelligent networked vehicles on the flow, density, speed and other characteristics of the traffic flow. The results show that when the proportion of intelligent networked vehicles in the traffic flow is 40% to 80%, with the increase in the proportion of intelligent networked vehicles, the operating speed of the traffic flow, the density of the traffic flow has been improved to varying degrees, and the road passable flow has also been improved.
Architected fibrous scaffolds for engineering anisotropic tissues
Authors: Reid James Alexander , Dwyer Kiera D , Schmitt Phillip R , Soepriatna Arvin H , Coulombe Kareen LK , Callanan Anthony
Published: June 2021

Mimicking the native three-dimensional microenvironment is of crucial importance when biofabricating a new healthcare material. One aspect of the native tissue that is often omitted when designing a suitable scaffold is its anisotropy. Not only is matching native mechanical properties important when designing implantable scaffolds or healthcare materials, but matching physiological structure is also important as many cell populations respond differently to fiber orientation. Therefore, novel aligned electrospun scaffolds with varying fiber angles and spacing of bundles were created and mechanically characterized. Through controlling the angle between the fibers in each layer of the scaffold, a range of different physiological anisotropic mechanical properties were achieved that encompasses values found in native tissues. Extrapolation of this mechanical data allowed for any native tissue’s anisotropic Young’s modulus to be mimicked by electrospinning fibers at a particular angle. These electrospun scaffolds were then incorporated with cell-laden hydrogels to create hybrid structures that contain the benefits of both scaffolding techniques with the ability to encapsulate cells in the hydrogel. To conclude, this study develops a novel bundled fiber scaffold that was architected to yield anisotropic properties matching native tissues.
Effect of ultrasonic pretreatment on thermo-mechanical properties of epoxy adhesive
Authors: Wang Hui , Liu Zhaoyi , Chen Yizhe , Hua Lin , Qiu Yi
Published: June 2021

Ultrasonic vibration can accelerate the curing of epoxy resin. Previous studies have not clarified the mechanism of ultrasonic vibration for accelerating the curing of epoxy resins. And the mechanical and thermal properties of the adhesive after ultrasonic-accelerated curing have not been clearly analyzed. In this study, the conventional thermal and ultrasonic-assisted curing processes of the bicomponent adhesive 3 M DP420 were characterized by tensile testing, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis and Fourier transform infrared spectroscopy. The results show that the curing rate of the adhesive can be increased by 50% by ultrasonic pretreatment. The tensile test results show that ultrasonic pretreatment can increase the tensile strength by 30.9%. Pulsed ultrasonic treatment can keep the temperature of the adhesive stable during the pretreatment process, and does not excessively raise the temperature. The thermal analysis results show that pulsed ultrasonic treatment can accelerate the curing process without the loss of mechanical properties or thermal stability. It was observed that the glass transition temperature shifted to a higher value when the curing temperature increased. Ultrasonic vibration promotes mass transfer between the epoxy resin and curing agent and increases the collision probability between the reactants, thus increasing the reaction rate. In addition, it was found that the temperature field has a significant effect on the properties of the adhesive, and medium-temperature curing is more suitable for curing the adhesive.
Capturing practitioner perspectives on infrastructure resilience using Q-methodology
Authors: Kim Yeowon , Grimm Nancy B , Chester Mikhail V , Redman Charles L
Published: June 2021

In many disciplines, the resilience concept has applied to managing perturbations, challenges, or shocks in the system and designing an adaptive system. In particular, resilient infrastructure systems have been recognized as an alternative to traditional infrastructure, in which the systems are managed to be more reliable against unforeseen and unknown threats in urban areas. Perhaps owing to the malleable and multidisciplinary nature in the concept of resilience, there is no clear-cut standard that measures and characterizes infrastructure resilience nor how to implement the concept in practice for developing urban infrastructure systems. As a result, unavoidable subjective interpretation of the concept by practitioners and decision-makers occurs in the real world. We demonstrate the subjective perspectives on infrastructure resilience by asking practitioners working in governmental institutions within the metropolitan Phoenix area based on their interpretations of resilience, using Q-methodology. We asked practitioners to prioritize 19 key strategies for infrastructure resilience found in literature in three different decision contexts and recognized six discourses by analyzing the shared or discrete views of the practitioners. We conclude that, from the diverse perspectives on infrastructure resilience observed in this study, practitioners’ interpretation of resilience adds value to theoretical resilience concepts found in the literature by revealing why and how different resilience strategies are preferred and applied in practice.
Roles of leader and follower cells in collective cell migration
Authors: Qin Lei , Yang Dazhi , Yi Weihong , Cao Huiling , Xiao Guozhi
Published: June 2021

Collective cell migration is a widely observed phenomenon during animal development, tissue repair, and cancer metastasis. Considering its broad involvement in biological processes, it is essential to understand the basics behind the collective movement. Based on the topology of migrating populations, tissue-scale kinetics, called the “leader–follower” model, has been proposed for persistent directional collective movement. Extensive in vivo and in vitro studies reveal the characteristics of leader cells, as well as the special mechanisms leader cells employ for maintaining their positions in collective migration. However, follower cells have attracted increasing attention recently due to their important contributions to collective movement. In this Perspective, the current understanding of the molecular mechanisms behind the “leader–follower” model is reviewed with a special focus on the force transmission and diverse roles of leaders and followers during collective cell movement.
A new solution to the regress of pure powers
Authors: Taylor Henry
Published: June 2021

I offer a new response to the regress argument against pure powers ontologies. This involves rejecting an overlooked premiss, which is that a power’s manifestation is exhaustively accounted for by the powers involved in it. Rejection of this premiss not only answers the regress argument, but also brings with it wider metaphysical consequences, including a shift away from one-category ontologies.
Intra-Caribbean Solidarities and the Language of Social Protest
Authors: Hamm-Rodríguez Molly , Medina Carmen Liliana
Published: June 2021

This essay explores the language of social protest in two geographic and diasporic locations in the Caribbean (Puerto Rico and the Dominican Republic) with long and ongoing histories of colonialism and imperialism. We analyze social media and digital mobilizing to examine how, in the midst of social protest, linguistic and semiotic tools indexed historicity, contemporaneity, and futurity through relational strategies that are not just textual and discursive, but also historical, social, and political. Throughout this essay, we share examples of intertextual and interdiscursive strategies that marked particular moments of protest as articulations of historical precedents, imperial and colonial presents, and alternative futures. These examples reveal how collective identities (i.e. el pueblo) are mobilized in social protest to generate counternarratives that address structures and systems rather than locate social critiques in particular individuals and political parties. In shedding light on the intra-Caribbean solidarities that emerge over time, this analysis also points to a need to examine the erasures (Gal and Irvine 2019) performed through claims to unity and collective organizing.
Plotting for change: an analytical framework to aid decisions on which lineages are candidate species in phylogenomic species discovery
Authors: Unmack Peter J , Adams Mark , Hammer Michael P , Johnson Jerald B , Gruber Bernd , Gilles André , Young Matthew , Georges Arthur
Published: June 2021

A recent study argued that coalescent-based models of species delimitation mostly delineate population structure, not species, and called for the validation of candidate species using biological information additional to the genetic information, such as phenotypic or ecological data. Here, we introduce a framework to interrogate genomic datasets and coalescent-based species trees for the presence of candidate species in situations where additional biological data are unavailable, unobtainable or uninformative. For de novo genomic studies of species boundaries, we propose six steps: (1) visualize genetic affinities among individuals to identify both discrete and admixed genetic groups from first principles and to hold aside individuals involved in contemporary admixture for independent consideration; (2) apply phylogenetic techniques to identify lineages; (3) assess diagnosability of those lineages as potential candidate species; (4) interpret the diagnosable lineages in a geographical context (sympatry, parapatry, allopatry); (5) assess significance of difference or trends in the context of sampling intensity; and (6) adopt a holistic approach to available evidence to inform decisions on species status in the difficult cases of allopatry. We adopt this approach to distinguish candidate species from within-species lineages for a widespread species complex of Australian freshwater fishes (Retropinna spp.). Our framework addresses two cornerstone issues in systematics that are often not discussed explicitly in genomic species discovery: diagnosability and how to determine it, and what criteria should be used to decide whether diagnosable lineages are conspecific or represent different species.
Deep Eutectic Solvent-Based Microwave-Assisted Extraction for the Chromatographic Analysis of Bioactive Flavonoids in Spirodela polyrrhiza
Authors: Hao Haitian , Lin Long , Liu Shun , Kang Yun , Wang Yaqin , Huang Jianming , Weng Weiyu
Published: June 2021

Deep eutectic solvents (DESs) are regarded as promising solvents to extract chemicals from plant materials. In this study, a DES-based microwave-assisted extraction (MAE) method was developed for the chromatographic analysis of four bioactive flavonoids in Spirodela polyrrhiza. Chromatographic separation was achieved on a Promosil C18-column. Prior to the HPLC analysis, the flavonoids were rapidly extracted by a DES–MAE process using choline chloride/levulinic acid (1:2, mol/mol) as the solvent. The extraction parameters were optimized using response surface methodology, and the optimal DES–MAE was fast and efficient compared with conventional solvent-based MAE and ultrasonic-assisted extraction using DES. The recoveries of optimized DES–MAE for the four flavonoids ranged from 97.80 to 103.29%. This study demonstrates that the validated DES–MAE–HPLC method is efficient, accurate and applicable to the determination of flavonoids in S. polyrrhiza.
Differences in mitral valve geometry between atrial and ventricular functional mitral regurgitation in patients with atrial fibrillation: a 3D transoesophageal echocardiography study
Authors: Uno Goki , Omori Taku , Shimada Shunsuke , Rader Florian , Siegel Robert J , Shiota Takahiro
Published: June 2021

Aims

This study investigated geometric differences in mitral valve apparatus between atrial functional mitral regurgitation (A-FMR) and functional mitral regurgitation (FMR) with left ventricular (LV) dysfunction in patients with atrial fibrillation (AF) using 3D transoesophageal echocardiography (TOE).

Methods and results 

In total, 135 moderate or greater FMR patients with persistent AF or atrial flutter underwent 3D TOE. Fifty-six patients had A-FMR, defined as preserved LV ejection fraction (LVEF) of ≥50% and normal LV wall motion. Seventy-nine patients had ventricular FMR (V-FMR), defined as LV dysfunction (LVEF of <50%) or LV wall motion abnormality. To evaluate mitral leaflet coaptation, the coapted area was calculated as follows: total leaflet area (TLA) in end-diastole − closed leaflet area in mid-systole. Although annular area (AA) did not significantly differ between the two groups, TLA was significantly smaller in A-FMR than in V-FMR (P = 0.005). TLA/AA, indicating the degree of the leaflet remodelling, was significantly smaller in A-FMR than in V-FMR (P < 0.001). A-FMR had significantly smaller posterior mitral leaflet tethering height and angle measured at three anteroposterior planes (lateral, central, and medial) than V-FMR (all P < 0.001). However, vena contracta width (VCW) measured on long-axis view on TOE and coapted area, which correlated with VCW (r = −0.464, P < 0.001), were similar between the two groups.

Conclusion

Mitral leaflet remodelling may be less in A-FMR compared with V-FMR. However, leaflet tethering was smaller in A-FMR than in V-FMR, and this may result in a similar degree of mitral leaflet coaptation and mitral regurgitation severity.
Prevalence, management and impact of chronic obstructive pulmonary disease in atrial fibrillation: a systematic review and meta-analysis of 4,200,000 patients
Authors: Romiti Giulio Francesco , Corica Bernadette , Pipitone Eugenia , Vitolo Marco , Raparelli Valeria , Basili Stefania , Boriani Giuseppe , Harari Sergio , Lip Gregory Y H , Proietti Marco ,   the AF-COMET International Collaborative Group, Akao Masaharu , Barrett Tyler Warren , Campanini Mauro , Fauchier Laurent , Guo Yutao , Gussoni Gualberto , Jani Bhautesh D , Jenkins Cathy A , Kulić Mehmed , Mair Frances , SorianoMarcolino Milena , Naser Nabil , O'Brien Emily C , Ogawa Hishashi , Paixão Gabriela MM , Piccini Jonathan P , Ribeiro Antonio Luiz , Rodriguez-Mañero Moisãs
Published: June 2021

Aim

Prevalence of chronic obstructive pulmonary disease (COPD) in atrial fibrillation (AF) patients is unclear, and its association with adverse outcomes is often overlooked. Our aim was to estimate the prevalence of COPD, its impact on clinical management and outcomes in patients with AF, and the impact of beta-blockers (BBs) on outcomes in patients with COPD.

Methods and results

A systematic review and meta-analysis was conducted according to international guidelines. All studies reporting the prevalence of COPD in AF patients were included. Data on comorbidities, BBs and oral anticoagulant prescription, and outcomes (all-cause death, cardiovascular (CV) death, ischaemic stroke, major bleeding) were compared according to COPD and BB status. Among 46 studies, pooled prevalence of COPD was 13% [95% confidence intervals (CI) 10–16%, 95% prediction interval 2–47%]. COPD was associated with higher prevalence of comorbidities, higher CHA2DS2-VASc score and lower BB prescription [odds ratio (OR) 0.77, 95% CI 0.61–0.98]. COPD was associated with higher risk of all-cause death (OR 2.22, 95% CI 1.93–2.55), CV death (OR 1.84, 95% CI 1.39–2.43), and major bleeding (OR 1.45, 95% CI 1.17–1.80); no significant differences in outcomes were observed according to BB use in AF patients with COPD.

Conclusion

COPD is common in AF, being found in 13% of patients, and is associated with increased burden of comorbidities, differential management, and worse outcomes, with more than a two-fold higher risk of all-cause death and increased risk of CV death and major bleeding. Therapy with BBs does not increase the risk of adverse outcomes in patients with AF and COPD.
Longleaf Pine (Pinus palustris Mill.) Branch Pruning by Prescribed Fire
Authors: McGuire John P , Kush John S , Varner J Morgan , Lauer Dwight K , Mitchell J Ryan
Published: June 2021

Efforts to restore longleaf pine (Pinus palustris Mill.) in the southeastern US require substantial artificial regeneration. Once established, important questions remain about when to introduce fire. We investigated the impact of initial planting density on tree branching and how prescribed fire might interact with tree architecture and survival. A particular focus was on how prescribed fires could “prune” lower branches. Lower density plantings (897 trees ha−1) had more and larger live lower branches than higher density plantings (2,243 trees ha−1). Fire was effective in pruning lower branches regardless of season burned, but fire in the growing season was more effective at pruning. Branches up to a height of 1.5 to 2 m were killed by fire. Fire applied in August caused greater damage with more needles scorched and/or consumed and more stem char. Prescribed fire did not impact longleaf pine tree survival. In general, fire applied to longleaf pine facilitated pruning lower branches that affect long-term wood quality, an additional argument for its utility in restoration and management of these ecosystems.
How Widowhood and Gender Shape the Impact of Maternal Favoritism on Adult Children’s Psychological Well-Being
Authors: Suitor J Jill , Gilligan Megan , Kincaid Reilly , Hou Yifei , Stepniak Catherine , Peng Siyun
Published: June 2021

Objectives

Our goal was to extend research on within-family differences in mother–child relations in later life by focusing on 2 social structural characteristics of mothers and offspring that may play important roles in shaping the impact of maternal favoritism on adult children’s depressive symptoms—mother’s marital status and child’s gender.

Methods

Mixed-methods data were collected as part of the Within-Family Differences Study from 641 adult children nested within 273 families in which: (a) there were at least 2 living adult siblings, and (b) mothers were married or widowed.

Results

Multilevel analyses indicated that perceiving oneself as the child to whom one’s mother was most emotionally close was a strong predictor of higher depressive symptoms among daughters of widowed mothers; in contrast, perceptions of favoritism did not predict depressive symptoms among sons of either widowed or married mothers, or daughters of married mothers. Qualitative analyses revealed that daughters, but not sons, of widowed mothers tended to attribute their greater closeness with their mothers to their roles as their mothers’ “emotional caregivers,” particularly solo caregivers, during times when mothers faced negative life events that neither they nor their children could control or ameliorate.

Discussion

The quantitative and qualitative findings we present underscore how social structural positions—in this case, mother’s marital status and child’s gender—combine with social psychological processes to shape how parent–child relations affect children’s well-being in adulthood.
BIGwas: Single-command quality control and association testing for multi-cohort and biobank-scale GWAS/PheWAS data
Authors: Kässens Jan Christian , Wienbrandt Lars , Ellinghaus David
Published: June 2021

Background

Genome-wide association studies (GWAS) and phenome-wide association studies (PheWAS) involving 1 million GWAS samples from dozens of population-based biobanks present a considerable computational challenge and are carried out by large scientific groups under great expenditure of time and personnel. Automating these processes requires highly efficient and scalable methods and software, but so far there is no workflow solution to easily process 1 million GWAS samples.

Results

Here we present BIGwas, a portable, fully automated quality control and association testing pipeline for large-scale binary and quantitative trait GWAS data provided by biobank resources. By using Nextflow workflow and Singularity software container technology, BIGwas performs resource-efficient and reproducible analyses on a local computer or any high-performance compute (HPC) system with just 1 command, with no need to manually install a software execution environment or various software packages. For a single-command GWAS analysis with 974,818 individuals and 92 million genetic markers, BIGwas takes ∼16 days on a small HPC system with only 7 compute nodes to perform a complete GWAS QC and association analysis protocol. Our dynamic parallelization approach enables shorter runtimes for large HPCs.

Conclusions

Researchers without extensive bioinformatics knowledge and with few computer resources can use BIGwas to perform multi-cohort GWAS with 1 million GWAS samples and, if desired, use it to build their own (genome-wide) PheWAS resource. BIGwas is freely available for download from http://github.com/ikmb/gwas-qc and http://github.com/ikmb/gwas-assoc.
Measuring Trade Cost Reductions Through a New Bridge in Mozambique: Who Benefits From Transport Infrastructure?
Authors: Zant Wouter
Published: June 2021

We use spatial maize prices in Mozambique to measure transport cost reductions, attribute these reductions to road distance and road quality and assess to what extent producers, traders and consumers benefit. For identification we exploit a unique natural experiment, the construction of a new road bridge over the Zambezi River, which connects the north and south of Mozambique. The applied methodology allows for potentially oligopolistic traders with spatially varying mark-ups. Estimations are based on monthly maize prices, in 22 markets, for 5 years before and after the introduction of the bridge. Estimates of transport cost reductions, averaged over routes, vary from 3% to 7%, with large heterogeneity between routes, and roughly for two-third due to road distance and for one-third due to road quality. On average benefits of trade cost reductions are equally shared between traders and consumers, but for larger distances, a larger part accrues to traders. The evidence also indicates a reduction in prices in destination markets due to the bridge. Results are supported by observed transport cost data, robust for non-random bridge placement and strict source-destination rules.