bluuebunny/crossref_metadata_2025 huggingface dataset:
Traffic System Optimization Model Based on Travel Demand of Multi-mode Traffic Network
Authors: Yang Xinzheng , Zhou Kang , Peng Xiao
Published: October 2020

The urban multi-mode traffic system, which is composed of rail transit, bus and trolley bus, taxi (including online car Hailing), bicycle and walking, provides the basic guarantee for the daily travel of urban residents. Based on the analysis of urban multi-mode transportation system and network characteristics, the directed network diagram of multi-mode transportation system is constructed. Based on the research methods of related fields at home and abroad, aiming at the characteristics of urban residents’ travel, especially commuting travel, a multi-objective optimization model of urban residents’ travel scheme analysis from the perspective of travel time, travel cost, etc. is constructed. Considering the non-linear characteristics of the model, the multi-objective model is transformed into a single objective model, and the model is solved by CPLEX optimization software. Finally, the applicability and reliability of the model are verified by an example.
Method for optimizing the allocation of the following car schedule based on minimum running time
Authors: Wu Xingyu
Published: October 2020

Rail transit has become one of the most important means of transportation in various countries, which brings huge energy consumption. This paper studies how to allocate the running time of trains between multiple stations to adjust the schedule, to achieve the purpose of energy-saving. Before time allocation between multiple stations, there must be an optimal operation strategy for single-station trains. Studies have shown that under the optimal operation strategy, the longer the time, the smaller the energy consumption, and the remaining redundant time is allocated based on the minimum time. The train operation schedule can reduce energy consumption. In the first phase of this paper, the minimum running time between stations is modeled and solved. Based on this, the existing optimal operation strategy is used to obtain the time and energy consumption relationship curve. In the second phase, the operation redundancy is allocated based on the train energy consumption time relationship model. In terms of time, the optimized energy-saving schedule is obtained to achieve the purpose of energy-saving train.
Evaluation on Optimization of Traffic Organization of Xiangfang Wanda Parking Lot
Authors: Guo Yu
Published: October 2020

With the rapid growth of per capita car ownership, urban parking demand has increased sharply, and the contradiction between parking supply and demand has become increasingly prominent. Part of the reason for this problem is that under the conditions of the existing transportation facilities, the functions of parking facilities are not adequate Play. This paper takes the Xiangfang Wanda underground parking lot in Harbin City as the research object. Through questionnaires and observation records, the parking lot is investigated and analyzed. The parking lot is optimized by qualitative and quantitative methods, and finally based on fuzzy synthesis. Evaluation.
Research on the impact of building blasting vibration on the safety of adjacent subway structures
Authors: Zhang Qingqing , Guo Yangyang , Zhong Huarong , Miao Tong , Wang Xuewei
Published: October 2020

When using controlled blasting technology to demolish a building, the blasting vibration caused by the blasting process may harm the surrounding structure of the blasting area. To study the influence of blasting vibration on the adjacent subway structure, this paper takes the blasting demolition of a building in Chengdu as an example, analyzes the load during the blasting process, establishes the stratum-structure and load-structure finite element models of the subway structure, and simulates the dynamic response process of the structure, and then studies the safety impact of blasting demolition vibration on the adjacent subway structure. Studies have shown that: under the blasting construction scheme in this paper, the impact of blasting vibration on the subway structure is within a safe and controllable range.
Research on the Optimization of external traffic organization of urban passenger station Based on VISSIM Simulation
Authors: Yin Yuexiu , Tian Na , Liu Liqiang
Published: October 2020

In order to ensure the normal operation of the bus terminal, the external traffic organization of the bus terminal is studied. This article takes Xi’an Chengnan passenger station as an example, analyzes its external traffic organization in detail, and finds out the problems in the traffic organization of the passenger station based on the survey results. Then, according to the requirements of the external transportation organization, a scheme for optimizing the external transportation organization was proposed, which was carried out using VISSIM simulation software, and the feasibility of the optimization scheme was verified.
Research on High-Risk Road Sections Identification and Driving Early Warning System in Mountainous Areas Based on Edge-Cloud Integration Technology
Authors: Ting Shang , Jie Tang , Zhenyu Peng , Yanchen Li , Fengxi Xie
Published: October 2020

The operation of mountainous highways is of high risks and the emergency rescue after an accident is of great difficulty. Affected by the mountains, river densities and other topographic features, highways in mountainous areas are characterized by linear complexity, long span bridge and tunnel group, frequent transitions among subgrade-bridge-tunnel, steep slopes, complex setup of interchange, changeable climate and easy occurrence of secondary accident, etc. In the 5G Internet era, the artificial intelligence theories and methods continue to deepen. To fully integrate emerging information technologies such as computer vision and Edge-cloud Integration to establish a high-risk road sections identification and driving early warning system in mountainous areas will help drivers to drive, promote the intellectualization of mountainous highways, and improve the safety of traffic operation management. In this paper, the Edge-cloud Integration technology and the navigation map data, combined with vehicle vision, are used to establish an early traffic warning system. This system collects and shares data through vehicle-mounted terminal and navigation map, uses Matter-element Model to identify and measure risk in cloud, and feeds back the results to vehicle-mounted terminal. If the identification result shows that it is the high-risk sections, combined with the navigation map, there will be a voice warning to ensure driving safety.
Analysis of the Causes and Countermeasures of Chengdu City Road Traffic Noise
Authors: Chen Li Chun , Bo Fang , Xu He , Cai Jie , Li Dong
Published: October 2020

As the pace of urbanization in Chengdu continues to accelerate, the construction of urban roads has also been strengthened.2015 forming a dense urban road network. People often say that the city is too noisy. In fact, from a professional point of view, it is urban road noise. Therefore, under the influence of more and more people from urban road noise, it is necessary to investigate the generation and impact of urban road noise and related prevention measures. This article explains the causes and hazards of Chengdu’s road noise, and puts forward opinions and suggestions on urban road noise in order to provide some research materials for the same type of urban noise prevention.
Comparative Study on Air Transport Network Structure of China, US and EU
Authors: Lu Yan
Published: October 2020

Modern air transport is an important part of national economy, however, the air transport construction of China still lags behind developed countries. Here we construct the air transport networks of China, US and EU by taking cities as nodes and airlines as edges to study their characteristics comparatively. Through observing the statistical results of topological indices included degree, excess average degree and betweenness, we find the less branch airlines and the higher workload of hub cities are the factors restricting the air transport network of China. Then based on the indices sorts, we classify the air transport cities into global hub nodes, regional hub nodes and general nodes to show their different importance in the network. We consider that it is necessary to increase the numbers of global hub nodes and branch airlines, and improve their invulnerable abilities. This paper may provide references for guiding the air transport network construction of China.
Analysis of Beijing-Guangzhou High-Speed Railway Competitiveness Based on Generalized Travel Cost Model
Authors: Zeng Ning , Wang Zhimei
Published: October 2020

After the completion of the Beijing-Guangzhou high-speed railway, this paper studies the market sharing rate of the normal-speed railway, high-speed railway and civil aviation aircraft in the Beijing-Guangzhou line, and the broad travel cost of passengers. Ticket price, speediness, safety, comfort, convenience and punctuality are selected as evaluation indexes. Combined with the improved Logit model, a multiple discrete choice model of passenger travel is established. Then this paper investigates the travel intention of passengers and the actual data needed for model indicators. At last, the share rate of various modes of transportation in the Beijing-Guangzhou under the circumstances of different distances and different time values is predicted, as well as the impact of air fares on the competitiveness of high-speed rail products.
The Situation and Challenge of China’s Legal Inspection System of Ships
Authors: Song Gao
Published: October 2020

Ship inspection is a highly professional and technical administrative permission work, which is the first link to ensure the safety of navigation and operation of the ship. Under the new situation of powerful transportation and high-quality development, we need to reexamine the development connotation of China‘s legal inspection system, analyze the problems existing in the existing ship inspection and inspection management system, clarify the challenges and opportunities faced by the ship inspection system, initially put forward effective solutions, and provide necessary decision-making reference for the standardized construction of ship inspection management.
Correlation analysis between OD demand and traffic flow in urban traffic network
Authors: Luo Xiao , Li Juan
Published: October 2020

Traffic congestion has become a serious problem in urban area. It may be alleviated by effectively controlling the external conditions affecting the traffic networks. In this paper, various traffic assignment methods are employed to analyze the correlation between OD demand and traffic flow in urban traffic network. To explore the effects of external conditions, three algorithms including all or nothing algorithm, Dial algorithm and MSA algorithm are applied for traffic networks. We study the sensitivity of traffic assignment methods with variation of external conditions (e.g. the number of road sections, the number of intermediate nodes, the number of OD pairs). The comparison results show that the degree of influences depends on OD demands. Additionally, the traffic congestion can be alleviated by removing the node or sections of traffic networks, which can be used to develop traffic management strategies.
Measurement of Economic Contribution of Small and Medium Airports and Its Enlightenment to Region Economic Development
Authors: He Hang , He Xiao , Han Zhu , Wang Shuai
Published: October 2020

Based on the study of the influence mechanism of airports on regional economic development, this paper empirically analyzes the interaction between small and medium-sized airports and regional economic development by using the data of Mianyang Nanjiao airport from 2002 to 2017, in order to provide measurement methods and theoretical support for local governments to encourage and promote the development of local airports. In the part of empirical analysis, firstly, this paper constructs the air transport scale index system of small and medium-sized airports and the evaluation index system of regional economic development. Then, the entropy method is selected to select the key factors of the airport, so as to obtain the airport transportation capacity equivalent, and the principal component analysis method is used to extract the high load index of the regional economic system. Finally, this paper establishes the SVAR model of airport transportation capacity and regional economic relationship, carries out structural impulse response and variance decomposition analysis, draws the conclusion that small and medium-sized airports have a positive impact on regional economic development, but not significant, and analyzes the reasons.
Evaluation of freight logistics delayed efficiency in China
Authors: Donglong Wu , Xiangqian Wang , Dan Xia
Published: October 2020

In order to improve the development quality of China’s freight logistics, improve the efficiency of resource utilization, the article uses ARIMA-SVR-DEA method to forecast the freight logistics in our country delayed data and calculate the delayed freight logistics efficiency, and the results show that the unreasonable utilization of resources is the reason for the inefficiency of freight logistics, which provides a reference for the development of freight logistics industry.
SMEs Perception towards Adoption of Measurement System Analysis Strategy: A Case Study in Pump Manufacturing Industry
Authors: Varun Kumar T. , Ramya G. , Kowsalya P. , Shanmuga Priya B. , Tharani P.
Published: October 2020

Every industry from large scale to small scale is nowadays seeking for their continuous improvement. It is necessary to compare the performance of the measurement processes with the standard systems. In a typical scenario, one of the two processes represents an attempt to improve the other process, and one must determine if the attempt has been successful. Since repeatability and reproducibility (R&R) studies are often used to determine the adequacy of each measurement process separately, it is suitable to compare the results of these studies to determine if there is any difference in the variability of the two processes. In this paper, we consider R&R studies with two factors of parts and operators. We consider situations where the operator factor can be either random or fixed. Each operator makes repeated measurements on each part in a sample of process output and the different operators are used for each measurement process and the parts used for measurements are the same. A ratio commonly used to determine the adequacy of a single measurement process is used to compare the variability of the two measurement processes. Two statistical tests a result for differences in their ratio depends on their confidence intervals are proposed and compared using computer simulation. Finally, our study enables delegates to assess the performance of new and existing measurement systems.
A review on Friction Stir Welding in Aluminium Alloys
Authors: Stephen Leon J , Bharathiraja G , Jayakumar V
Published: October 2020

Joining of aluminium alloys is always a challenging task due to its easily oxidising property in its molten stage. Although its application is huge in the building of aerospace structure, 2XXX and 7XXX series alloys are categorised as non-weldable aluminium alloys. Recent development in the application of friction stir welding process in the joining of these non-weldable alloys simplified the fabrication processes. In this review article, significance of friction stir welding comparing with other solid state metal joining process is addressed. Recent developments and application of this relatively new metal joining process in various industries are also discussed. Particular emphasis has been given to the mechanism responsible for the formation of this solid state joining technique. Apart from this, major process parameters that influence the formation of weld and weld defects caused by the improper selection of process parameters are also explained in detail.
Influence of Boron Carbide Addition on Particle Size of Copper Zinc Alloys Synthesized by Powder Metallurgy
Authors: Rajeshkumar L. , Suriyanarayanan R. , Shree Hari K. , Venkatesh Babu S. , Bhuvaneswari V. , Jithin Karunan M.P.
Published: October 2020

Material systems with the combination of metals and non-metals forming an alloy systems has numerous advantages when compared with the monolithic materials. Synthesizing such materials systems can easily be done by many solid state processing methods. Copper Zinc (Cu-Zn) forms a ductile material system finding its applications in various conductive and tribological applications. Nano composites finds lot more applications due to the high specific area occupied by the particles. Focus of the current project is on the study of influence of Boron Carbide (B4C) powders addition into the Cu-Zn matrix while synthesizing them through high energy ball milling. B4C powders are added to the matrix at 10 % by volume. Particle size of the powder are determined by Scherer and Williamson-Hall synthesis methods after characterizing the milled powders by X-Ray diffraction (XRD). As the B4C powders are brittle, maximum volume fraction of these powders are expected to influence particle size of Cu-Zn alloy powders. Powder morphology is analysed by scanning electron microscopy (SEM). Influence of B4C powder particles upon grain size of Cu-Zn alloy powder blends was very minimum due to the tendency of particles to get saturated with respect to particle size after repeated milling.
A Review on Submerged Friction Stir Welding of Light Weight Alloys
Authors: Sucharitha M. , Ravi Sankar B. , Umamaheswarrao P.
Published: October 2020

Friction stir welding gained wide acceptance in many industries owing to its capability of joining lightweight materials, the subsequent development to Friction stir welding (FSW) was to submerge workpiece in liquids during welding termed as submerged friction stir welding (SFSW) resulted in improving mechanical properties. However, joint efficiency was much dependent on the process parameters. Hence, the present work aimed to consolidate the research works available in underwater friction stir welding (UFSW) primarily focusing on effect of process parameters on weld joint.
CuO-nano based Biodegradable Refrigeration Oil in R134a Refrigeration Systems for Energy Conservation and Green Environment
Authors: Vithya P. , Sriram G. , Arumugam S. , Aditya Chaitanya M.D.V. , Surya Deepak G. , Sriram Kumar K. , Jayaram Chandra P.
Published: October 2020

The present study experimentally investigated the reliability and performance of a vapour compression refrigeration system with CuO nano based biodegradable refrigeration oil. The pentaerythritol ester biodegradable refrigeration oil (PE) is blended with synthetic refrigeration oil (ISO 68 grade-POE oil) in the fraction of 50% by volume. Nanolubricant was synthesized on the basis of the concept of the nanofliuds, which was prepared by mixing CuO nanoparticles with pentaerythritol ester based biodegradable refrigeration oil blend (PE50). The concentration of nano CuO ranges in the order of 0.1% to 0.3% by weight with particle size of 40 nm to prepare CuO nano biodegradable refrigeration oil. An experimental test rig is designed and fabricated indigenously to carry out the investigations. The results indicated that CuO nano-based biodegradable refrigeration oil works normally and safely in the system. The compressor power consumption was reduced by 5.02% with the use of 0.3% CuO nano biodegradable refrigeration oil. The PE50 with 0.3% CuO nano has a considerable rise in coefficient of performance (COP) of about 45%. Hence CuO nano-based biodegradable refrigeration oil in refrigeration system considerably reduces the energy consumption and increases the COP of the refrigeration system.
Review on Thermal analysis of Polymer Matrix Composites
Authors: Venkatakoteswararao G. , Vinayagamoorthy R.
Published: October 2020

Natural fibers are widely used for reinforcement in composite materials and well tried to be effectively exchange fibre strengthened chemical compound composites to some extent in applications like domestic, automotive and lower finish region elements. A few explores have been investigated in last decades to research the conduct of natural fiber composites. The natural fibre strengthened composites are atmosphere friendly, have high strength to weight quantitative relation like artificial optical fiber strengthened composites. Deferential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) were used to evaluate the thermal properties. TGA is used to measure temperature change and mass loss of samples and DSC enables the measurement of glass transition temperature. This article presents an extensive study on the thermal properties of polymeric composites; the examination on polymeric composites is consistently in the phase of improving the properties.
Effect of Nano Particles on Tribological Behavior of Reciprocating Air Compressor Oil Using Fourball Tribometer: An Experimental Investigation
Authors: Chenga Reddy P. , Arumugam S.
Published: October 2020

This paper presents an experimental investigation of tribological properties of pentaerythritol ester (PE) as biolubricant with the addition of nanoparticles i.e. copper oxide (CuO). The nano particle was added with pentaerythritol ester by wt.% as 0.1, 0.3 and 0.5%. The experimental work was conducted on a fourball tribometer under various conditions such as applied load of 40 kg, speed of 1200 rpm, experimental duration of 1 hr and a temperature of 75°C under the standard of ASTM 4172. The 0.3% PE based nanoparticle lubricant shows the low coefficient of friction (COF), frictional torque (FT) and wear scar diameter (WSD) as compared to other nano based lubricants and with base oil. The tested worn surface was examined with SEM analysis and results are reported that the 0.3% nanoparticle lubricant shows the smoother and low surface roughness.
Eco Friendly Machining Processes for Sustainability - Review
Authors: Rajmohan T. , Kalyan Chakravarthy V.V. , Nandakumar A. , Satish Kumar S.D.
Published: October 2020

Green manufacturing is a style for industrialized that minimizes dissipate and contamination. The pollution prevention resolves in manufacturing industries to expand and execute various environmentally-friendly strategies. The main purpose of green machining is to hold up future generations by attaining sustainability. Cutting fluids are discoloured with metal particles and foulness products which reduce the efficiency of cutting fluids. To minimize the unpleasant environmental effects coupled with the use of cutting fluids, the harmful components from their formulations have to be eliminated or reduced to the acceptable level. In addition, mineral based cutting fluids are going to be replaced with vegetable based cutting fluids since they are environmentally friendly. The present review primarily determined on examining different aspects of machining process from an environmental sensitivity. This paper presents the environmental green machining such as dry machining, machining with minimum quantity lubricant, Cryogenic machining, hot machining, vegetable oil-based cutting fluids and nano filled cutting fluids. The Performance of Eco-friendly machining are discussed in terms of cutting forces, tool flank wear, cutting temperatures and surface finish are also discussed.
Biomass porous carbon-based composite for high performance supercapacitor
Authors: Wang Huilin , Wen Jie
Published: October 2020

Biomass porous carbons with abundant pore structure, surface functional groups, and excellent electrical conductivity, are widely used for electrode materials. In this work, biomass carbon with 3D mesh structure was loaded with metal sulfide to synthesize porous carbon-based ultrathin Ni3S2layered nanosheet structure supercapacitor composite material electrode. C/Ni3S2-16 showed 600 F g−1of high specific capacitance with 20 A g−1current density. After 5,000 charge and discharge cycles, 88.8% of the maximum (imital) specific capacitance was maintained at 10 A g−1. The assembled C/Ni3S2-16//C asymmetric supercapacitor achieved an energy density of up to 35.7 Wh Kg−1, which was remained at 27.9 Wh Kg−1with a high power density at 1500 W kg−1. Developed pore structure of biomass porous carbon provide sufficient space for the electrolyte in and out of the electrode, therefore the potentially high electrochemical activity and energy density of the transition metal sulfide were fully exhibited.
The mortality rate of Parkinson’s disease and related comorbidities: a nationwide population-based matched cohort study in Korea
Authors: Yoon Seo Yeon , Shin Jaeyong , Kim Yong Wook , Chang Jee Suk , Won Kim Hye
Published: October 2020

Background

previous studies on mortality of Parkinson’s disease (PD) enrolled a relatively small number of participants and were conducted in western countries. The objective of this study was to evaluate mortality rate of PD using a large nationwide cohort in Korea and to evaluate effects comorbidities have on mortality in PD.

Methods

the nationwide population-based cohort study was conducted using the Korean National Health Insurance Service—National Sample Cohort data. Patients with a primary diagnosis of PD were selected from the database. A matched cohort without PD was enrolled through randomly matching patients by sex, age, year of diagnosis, residential area and income level to the PD group with a ratio of 1:9. The Cox proportional hazard model was used to assess mortality risk between the two cohorts. A logistic regression analysis was used to identify mortality risk factors in PD cohort.

Results

in total, 25,620 patients were enrolled. The Cox proportional regression model had an adjusted hazard ratio of 2.479 [95% confidence interval (CI), 2.272-2.704] for mortality in PD cohort. Comorbidities, such as ischaemic stroke [odds ratios (OR) = 2.314, 95% CI, 1.895-2.824], haemorrhagic stroke (OR = 2.281, 95% CI, 1.466-3.550) and chronic obstructive pulmonary disease (OR = 1.307, 95% CI, 1.048-1.630) were associated with increased mortality, whereas dyslipidemia (OR = 0.285, 95% CI, 0.227-0.358) was negatively correlated with mortality.

Conclusion

over the 10 year follow-up period, the PD cohort’s mortality rate was 2.5 times higher than the comparison cohort. Understanding the effects that comorbidities have on morality in PD would be useful for predicting mortality in patients with PD.
Optimized combination methods for exploring and verifying disease-resistant transcription factors in melon
Authors: Wang Zhicheng , Luan Yushi , Zhou Xiaoxu , Cui Jun , Luan Feishi , Meng Jun
Published: October 2020

A large amount of omics data and number of bioinformatics tools has been produced. However, the methods for further exploring omics data are simple, in particular, to mine key regulatory genes, which are a priority concern in biological systems, and most of the specific functions are still unknown. First, raw data of two genotypes of melon (susceptible and resistant) were obtained by transcriptome analysis. Second, 391 transcription factors (TFs) were identified from the plant transcription factor database and cucurbit genomics database. Then, functional enrichment analysis indicated that these genes were mainly annotated in the process of transcription regulation. Third, 243 and 230 module-specific TFs were screened by weighted gene coexpression network analysis and short time series expression miner, respectively. Several TF genes, such as WRKYs and bHLHs, were regarded as key regulatory genes according to the values of significantly different modules. The coexpression network showed that these TF genes were significant correlated with resistance (R) genes, such as DRP2, RGA3, DRP1 and NB-ARC. Fourth, cis-acting element analysis illustrated that these R genes may bind to WRKY and bHLH. Finally, the expression of WRKY genes was verified by quantitative reverse transcription PCR (RT-qPCR). Phylogenetic analysis was carried out to further confirm that these TFs may play a critical role in Curcurbitaceae disease resistance. This study provides a new optimized combination strategy to explore the functions of TFs in a wide spectrum of biological processes. This strategy may also effectively predict potential relationships in the interactions of essential genes.
COVID-19—Lessons Learned and Questions Remaining
Authors: Fang Ferric C , Benson Constance A , del Rio Carlos , Edwards Kathryn M , Fowler Vance G , Fredricks David N , Limaye Ajit P , Murray Barbara E , Naggie Susanna , Pappas Peter G , Patel Robin , Paterson David L , Pegues David A , Petri William A , Schooley Robert T
Published: October 2020

In this article, the editors of Clinical Infectious Diseases review some of the most important lessons they have learned about the epidemiology, clinical features, diagnosis, treatment and prevention of SARS-CoV-2 infection and identify essential questions about COVID-19 that remain to be answered.
A new water-soluble bacterial NADH: fumarate oxidoreductase
Authors: Bertsova Yulia V , Oleynikov Ilya P , Bogachev Alexander V
Published: October 2020

The cytoplasmic fumarate reductase of Klebsiella pneumoniae (FRD) is a monomeric protein which contains three prosthetic groups: noncovalently bound FMN and FAD plus a covalently bound FMN. In the present work, NADH is revealed to be an inherent electron donor for this enzyme. We found that the fumarate reductase activity of FRD significantly exceeds its NADH dehydrogenase activity. During the catalysis of NADH:fumarate oxidoreductase reaction, FRD turnover is limited by a very low rate (∼10/s) of electron transfer between the noncovalently and covalently bound FMN moieties. Induction of FRD synthesis in K. pneumoniae cells was observed only under anaerobic conditions in the presence of fumarate or malate. Enzymes with the FRD-like domain architecture are widely distributed among various bacteria and apparently comprise a new type of water-soluble NADH:fumarate oxidoreductases.
Phase-velocity inversion from data-based diffraction kernels: seismic Michelson interferometer
Authors: Chmiel Małgorzata , Roux Philippe , Wathelet Marc , Bardainne Thomas
Published: October 2020

We propose a new surface wave tomography approach that benefits from densely sampled active-source arrays and brings together elements from active-source seismic-wave interferometry, full waveform inversion and dense-array processing. In analogy with optical interferometry, seismic Michelson interferometer (SMI) uses seismic interference patterns given by the data-based diffraction kernels in an iterative inversion scheme to image a medium. SMI requires no traveltime measurements and no spatial regularization, and it accounts for bent rays. Furthermore, the method does not need computation of complex synthetic models, as it works as a data-driven inversion technique that makes it computationally very fast. In an automatic way, it provides high-resolution phase-velocity maps and their error estimation. SMI can complete traditional surface wave tomography studies, as its use can be easily extended from land active seismic data to the virtual source gathers of ambient-noise-based studies with dense arrays.
A semblance measure for model comparison
Authors: Commer Michael
Published: October 2020

Algorithmic and computational advances have made it possible that geophysical survey and earth model design can be aided by many systematic trial inverse-modelling runs with synthetic data. Such may, for example, come up in machine-learning approaches. Automated image appraisal pertaining to such applications will involve common statistical tests for goodness-of-data fit as a primary evaluation method. However, solution non-uniqueness may render multiple images equivalent in terms of their data fit, requiring secondary categorizers. A logical choice for classifying synthetic-imaging results quantifies the goodness of model fit where a known reference model replaces the observational input. The task of model intercomparison in terms of measuring the resemblance to the reference model poses challenges to common distance-based metrics like root mean square error and mean absolute error. First, distance-based metrics can introduce spurious contributions when smooth models with fuzzy target contours are to be compared against a sharp reference. Second, large differences due to parameter-estimation overshoots can dominate distance metrics. The remedy proposed here is referred to as semblance and is based on the idea of logistic functions, where a binary-dependent variable adds non-zero or zero accumulation terms for the, respectively, passing or failing of preset target thresholds. This classifying approach is amenable to an objective where model feature recognition is primary. Numerical comparisons to distance-based metrics provide evidence for the advantages of the semblance in view of this objective. Geophysical imaging in conjunction with machine-learning is seen as a benefitting upcoming application area.
Experimental test of the cooling rate effect on blocking temperatures in stepwise thermal demagnetization
Authors: Berndt Thomas A , Chang Liao , Paterson Greig A , Cao Changqian
Published: October 2020

Upon cooling, most rocks acquire a thermoremanent magnetization (TRM); the cooling rate at which this happens not only affects palaeointensity estimates, but also their unblocking temperatures in stepwise thermal demagnetization experiments, which is important, for example, to estimate volcanic emplacement temperatures. Traditional single-domain (SD) theory of magnetic remanence relates relaxation times to blocking temperatures— the blocking temperature is the temperature at which the relaxation time becomes shorter than the experimental timescale—and therefore strictly only applies to remanence acquisition mechanisms at constant temperatures (i.e. viscous remanent magnetizations, VRMs). A theoretical framework to relate (constant) blocking temperatures to (time-varying) cooling rates exists, but this theory has very limited experimental verification—partly due to the difficulty of accurately knowing the cooling rates of geological materials. Here we present an experimental test of this ‘cooling rate effect on blocking temperatures’ through a series of demagnetization experiments of laboratory-induced TRMs with controlled cooling rates. The tested cooling rates span about 1 order of magnitude and are made possible through (1) extremely accurate demagnetization experiments using a low-temperature magnetic properties measurement system (MPMS) and (2) the use of a ‘1-step-only’ stepwise thermal demagnetization protocol where the relaxation process is measured over time. In this way the relaxation time corresponding to the blocking temperature is measured, which can be done to much higher accuracy than measuring the blocking temperature directly as done in traditional stepwise thermal demagnetization experiments. Our experiments confirm that the cooling rate relationship holds to high accuracy for ideal magnetic recorders, as shown for a synthetic weakly interacting SD magnetoferritin sample. A SD-dominated low-Ti titanomagnetite Tiva Canyon Tuff sample, however, showed that natural samples are unlikely to be sufficiently ‘ideal’ to meet the theoretical predictions to high accuracy—the experimental data agrees only approximately with the theoretical predictions, which may potentially affect blocking temperature estimates in stepwise thermal demagnetization experiments. Moreover, we find a strongly enhanced cooling rate effect on palaeointensities for even marginally non-ideal samples (up to 43 per cent increase in pTRM for a halving of the cooling rate).
Corporate power and the international trade regime preventing progressive policy action on non-communicable diseases: a realist review
Authors: Milsom Penelope , Smith Richard , Baker Phillip , Walls Helen
Published: October 2020

Transnational tobacco, alcohol and ultra-processed food corporations use the international trade regime to prevent policy action on non-communicable diseases (NCDs); i.e. to promote policy ‘non-decisions’. Understanding policy non-decisions can be assisted by identifying power operating in relevant decision-making spaces, but trade and health research rarely explicitly engages with theories of power. This realist review aimed to synthesize evidence of different forms and mechanisms of power active in trade and health decision-making spaces to understand better why NCD policy non-decisions persist and the implications for future transformative action. We iteratively developed power-based theories explaining how transnational health-harmful commodity corporations (THCCs) utilize the international trade regime to encourage NCD policy non-decisions. To support theory development, we also developed a conceptual framework for analysing power in public health policymaking. We searched six databases and relevant grey literature and extracted, synthesized and mapped the evidence against the proposed theories. One hundred and four studies were included. Findings were presented for three key forms of power. Evidence indicates THCCs attempt to exercise instrumental power by extensive lobbying often via privileged access to trade and health decision-making spaces. When their legitimacy declines, THCCs have attempted to shift decision-making to more favourable international trade legal venues. THCCs benefit from structural power through the institutionalization of their involvement in health and trade agenda-setting processes. In terms of discursive power, THCCs effectively frame trade and health issues in ways that echo and amplify dominant neoliberal ideas. These processes may further entrench the individualization of NCDs, restrict conceivable policy solutions and perpetuate policymaking norms that privilege economic/trade interests over health. This review identifies different forms and mechanisms of power active in trade and health policy spaces that enable THCCs to prevent progressive action on NCDs. It also points to potential strategies for challenging these power dynamics and relations.
Parasite Viability as a Superior Measure of Antimalarial Drug Activity in Humans
Authors: Rebelo Maria , Pawliw Rebecca , Gower Jeremy , Webb Lachlan , Mitchell Hayley , Pava Zuleima , Watts Rebecca E , Davenport Miles P , McCarthy James S , Khoury David S
Published: October 2020

Background

Artemisinin derivatives are the leading class of antimalarial drugs due to their rapid onset of action and rapid clearance of circulating parasites. The parasite clearance half-life measures the rate of loss of parasites from blood after treatment, and this is currently used to assess antimalarial activity of novel agents and to monitor resistance. However, a number of recent studies have challenged the use of parasite clearance to measure drug activity, arguing that many circulating parasites may be nonviable.

Methods

Plasmodium falciparum–infected subjects (n = 10) in a malaria volunteer infection study were administered a single dose of artesunate (2 mg/kg). Circulating parasite concentration was assessed by means of quantitative polymerase chain reaction (qPCR). Parasite viability after artesunate administration was estimated by mathematical modeling of the ex vivo growth of parasites collected from subjects.

Results

We showed that in artemisinin-sensitive infection, viable parasites declined to <0.1% of baseline within 8 hours after artesunate administration, while the total number of circulating parasites measured with quantitative polymerase chain reaction remained unchanged. In artemisinin-resistant infections over the same interval, viable parasites declined to 51.4% (standard error of the mean, 4.6%) of baseline.

Conclusions

These results demonstrate that in vivo drug activity of artesunate is faster than is indicated by the parasite clearance half-life.
Serological Evidence of Human Infection With Avian Influenza A(H7N9) Virus: A Systematic Review and Meta-analysis
Authors: Wang Wei , Chen Xinhua , Wang Yan , Lai Shengjie , Yang Juan , Cowling Benjamin J , Horby Peter W , Uyeki Timothy M , Yu Hongjie
Published: October 2020

Background

The extent of human infections with avian influenza A(H7N9) virus, including mild and asymptomatic infections, is uncertain.

Methods

We performed a systematic review and meta-analysis of serosurveys for avian influenza A(H7N9) virus infections in humans published during 2013–2020. Three seropositive definitions were assessed to estimate pooled seroprevalence, seroconversion rate, and seroincidence by types of exposures. We applied a scoring system to assess the quality of included studies.

Results

Of 31 included studies, pooled seroprevalence of A(H7N9) virus antibodies from all participants was 0.02%, with poultry workers, close contacts, and general populations having seroprevalence of 0.1%, 0.2%, and 0.02%, respectively, based on the World Health Organization (WHO)—recommended definition. Although most infections were asymptomatic, evidence of infection was highest in poultry workers (5% seroconversion, 19.1% seroincidence per 100 person-years). Use of different virus clades did not significantly affect seroprevalence estimates. Most serological studies were of low to moderate quality and did not follow standardized seroepidemiological protocols or WHO-recommended laboratory methods.

Conclusions

Human infections with avian influenza A(H7N9) virus have been uncommon, especially for general populations. Workers with occupational exposures to poultry and close contacts of A(H7N9) human cases had low risks of infection.
Bayesian estimation of the seroprevalence of antibodies to SARS-CoV-2
Authors: Dong Qunfeng , Gao Xiang
Published: October 2020

Accurate estimations of the seroprevalence of antibodies to severe acute respiratory syndrome coronavirus 2 need to properly consider the specificity and sensitivity of the antibody tests. In addition, prior knowledge of the extent of viral infection in a population may also be important for adjusting the estimation of seroprevalence. For this purpose, we have developed a Bayesian approach that can incorporate the variabilities of specificity and sensitivity of the antibody tests, as well as the prior probability distribution of seroprevalence. We have demonstrated the utility of our approach by applying it to a recently published large-scale dataset from the US CDC, with our results providing entire probability distributions of seroprevalence instead of single-point estimates. Our Bayesian code is freely available at https://github.com/qunfengdong/AntibodyTest.
Growth performance and hematological changes of weaned beef calves diagnosed with respiratory disease using respiratory scoring and thoracic ultrasonography
Authors: Cuevas-Gómez Inmaculada , McGee Mark , McCabe Matthew , Cormican Paul , O’Riordan Edward , McDaneld Tara , Earley Bernadette
Published: October 2020

This study investigated 1) the effect of clinical bovine respiratory disease (BRD) and associated lung consolidations on growth performance and hematological profiles of recently weaned beef calves and 2) the relationship between clinical respiratory signs and lung consolidation detected by thoracic ultrasonography (TUS). One hundred and fifty-three weaned beef calves (209 days old [SD: 35.8] and 306 kg [SD: 26.3], at arrival) purchased and transported from auction markets were accommodated indoors in concrete slatted floor pens. Calves were weighed weekly from arrival until day 28 and on day 65 post-arrival. Assessment of BRD and blood sample collection for hematological profiles were performed on scheduled days (at arrival, on days 7, 14, and 28) and on other days upon BRD diagnosis. Animals were assessed for BRD using a total clinical respiratory score (CRS) of five clinical signs (rectal temperature, ear position, cough, nasal secretion, and eye secretion with each ranging from normal [0] to abnormal [3]) and TUS scores (normal [0] to lung consolidation ≥ 1 cm2 [2]). Based on CRS, 35% of calves were CRS+ (CRS ≥ 5) and 65% were CRS− (CRS < 5). Although no lung consolidations (TUS−) were detected at arrival, 34% of calves developed lung consolidation (≥1 cm2) (TUS+) during the first 28 d post-arrival. Only fever (>39.6 °C) and nasal discharge were weakly associated (r = 0.19, P <0.05) with lung consolidation. On the day of BRD detection, neutrophil number and neutrophil:lymphocyte ratio were 58% and 73% greater, respectively, in BRD calves with lung consolidation compared with healthy calves. From day 0 to 65, calf average daily gain (ADG) did not differ (P >0.05) between CRS+ and CRS− calves but was 0.09 kg/d lower (P < 0.05) for TUS+ compared with TUS− calves. Calves classified as BRD (CRS + TUS ≥ 5) with lung consolidation had lower (P < 0.05) ADG from arrival until day 28 than healthy calves and BRD calves without lung consolidation (0.11 ± 0.10 vs. 0.53 ± 0.07 vs. 0.57 ± 0.10 kg/d, respectively); however, no differences in ADG were observed from day 0 to 65. Conventional methods to diagnose BRD failed to detect calves with lung lesions. TUS is a useful tool to detect lung lesions and its implementation in combination with CRS should provide a more accurate and early diagnosis of BRD, which is fundamental to successful treatment, animal welfare, and growth performance.
Revealing the impact of quasar luminosity on giant Ly α nebulae
Authors: Mackenzie Ruari , Pezzulli Gabriele , Cantalupo Sebastiano , Marino Raffaella A , Lilly Simon , Muzahid Sowgat , Matthee Jorryt , Schaye Joop , Wisotzki Lutz
Published: October 2020

We present the results from a MUSE survey of twelve z ≃ 3.15 quasars, which were selected to be much fainter (20 < iSDSS < 23) than in previous studies of giant Ly α nebulae around the brightest quasars (16.6 < iAB < 18.7). We detect H i Ly α nebulae around 100 per cent of our target quasars, with emission extending to scales of at least 60 physical kpc, and up to 190 pkpc. We explore correlations between properties of the nebulae and their host quasars, with the goal of connecting variations in the properties of the illuminating QSO to the response in nebular emission. We show that the surface brightness profiles of the nebulae are similar to those of nebulae around bright quasars, but with a lower normalization. Our targeted quasars are on average 3.7 mag (≃30 times) fainter in UV continuum than our bright reference sample, and yet the nebulae around them are only 4.3 times fainter in mean Ly α surface brightness, measured between 20 and 50 pkpc. We find significant correlations between the surface brightness of the nebula and the luminosity of the quasar in both UV continuum and Ly α. The latter can be interpreted as evidence for a substantial contribution from unresolved inner parts of the nebulae to the narrow components seen in the Ly α lines of some of our faint quasars, possibly from the inner circumgalactic medium or from the host galaxy’s interstellar medium.
New Herbig–Haro objects and outflows in the Mon R1 association
Authors: Movsessian T A , Magakian T Yu , Dodonov S N
Published: October 2020

We present the results of a narrow-band Hα and [S ii] imaging survey of the Mon R1 association performed with the 1-m Schmidt telescope at Byurakan Observatory. Our observations covered a 1° field near the centre of the association. As a result of this study, 20 new Herbig–Haro knots were discovered, some of which form collimated outflows. Among the most extended ones are HH 1203 and HH 1196, which have a length of 1 pc or even more. During the search for the probable sources of HH objects, several new nebulous stars were found. A list of all nebulous stellar objects in the Mon R1 area under study is presented, with detailed descriptions of the most interesting ones. The near-infrared data from the GLIMPSE360 and WISE surveys revealed several more objects related to Mon R1, some of which had optical counterparts, as well as helped to identify at least three probable H2 collimated flows from the deeply embedded pre-main-sequence objects. The probable members of Mon R1 were selected by their distances; their bolometric luminosities and extinctions were estimated. Among the outflow sources, three embedded objects with luminosities greater than 10 L⊙ were found. The mean distance to the Mon R1 complex is estimated as 715 pc.