bluuebunny/crossref_metadata_2025 huggingface dataset:
Spin excitation kinetics in paramagnet by microwave field pulse
Authors: Asadullina N Y , Asadullin T Y
Published: April 2021

This work is devoted to the study of the kinetics of electron spins excitation in solid-state dilute paramagnets in the process of transient nutations. Transitional nutations are the response of a system, initially in thermal equilibrium, to a suddenly applied very intense resonance field during its transition to a new stationary state. The decay rate of the signal is determined by the interaction of active spins with each other Γac (Δ, t) ∼ nac (Δ, t) and active spins with passive Γpas (Δ, t) ∼ npas (Δ, t). Therefore, the challenge is to find these concentrations. They are obtained by solving kinetic (rate) equations.
Analysis of Intermediate Casing Wear in Ultra-deep Wells in China’s Tarim Oil Field
Authors: Ma Chao , Gao Baokui , Wang Jieli , Hu Tianxiang , Chen Xingwang
Published: April 2021

Intermediate casing wear with a spiral scar is often found in ultra-deep wells in Tarim Oil Field. In this work, the mechanism of such wear, and the measures to reduce wear are analyzed. Comparing the geometric characteristics of the wear scars, the root cause is found that the effective inner diameter of the casing is smaller than the outer diameter of the drill pipe joint after the uncemented casing helically buckled. To analyze the main factors affecting the helical buckling of the casing, the classical pipe mechanics theory is used and Well-X in Tarim area is taken as an example. The results show that too small hanging weight is the main cause of helical buckling of the casing. Besides downhole high temperature and large hole diameter enlargement rate are also important factors. The main measures, such as increasing the hanging weight, installing centralizers, and using graded cementation, have been proposed to reduce wear.
A Landing Impact Simulation Test Method for Lunar Lander
Authors: Zhang Wenbing , Li Dong , Zhu Jianbing , Qiu Hanping , Fan Shichao , Li Xinming , Zhang Jungang
Published: April 2021

The lunar lander shall be suffered transient impact load during the landing process. The structure’s ability of withstand the dynamic environment is the key to success of a soft landing. Therefore, it is necessary to conduct the simulation test of landing impact on the ground to examine and verify the structure of the lunar lander on the development stage of the lunar lander. This paper introduces the test system principle, composition and application design, and presents a method to simulate the landing surface material selection, of the design of lifting and releasing separation device, and the composition of measurement system. The test technique is both suitable for the verification test of the structure and the flight phase stage, and shall be carried out in a clean environment. The test method presented in this paper has been successfully applied in the Chang’e lunar landers.
Micro-vibration Test of High Resolution Spacecraft
Authors: Minghui Liu , Hui Cao , Chuang Liu , Xiaojian Han , Dong Wang , Jiang Yang
Published: April 2021

The accuracy of the high resolution earth observation spacecraft has remarkably increased in recent years. The micro-vibration induced by moving machine, such as moment wheels, may cause severe disturbance to the sensitive payload onboard the spacecraft. It is crucial to perform ground micro-vibration test to verify the observation performance of the spacecraft on orbit. This paper focuses on the system level micro-vibration test method of high resolution spacecraft. The key requirements of the micro-vibration test are firstly presented, and then the test system development is introduced. Finally, the micro-vibration application technique is given to demonstrate the whole process of the micro-vibration test. It is concluded that the test method and the test system are effective for the verification of the high resolution spacecraft.
Research on the Neal&Smith Criterion Application on Aircraft Flight Control System Handling Qualities Assessment
Authors: Guo Wei
Published: April 2021

This paper utilized Neal&Smith criterion to quantify handling qualities of some aircraft augmented with Control and Stability Augmentation System (CSAS) over the flight envelop. Some aircraft mathematical model which augmented by longitudinal pitch Rate Command-Attitude Hold(RCAH) controller are employed. The aircraft handling qualities are described in terms of transfer functions of the pilot mathematical model, which includes a pilot’s neuromuscular delay, phase and gain compensation terms. If desirable closed loop dynamic performance can be obtained by the pilot mathematical model described by transfer function characteristics, then the satisfactory closed loop dynamic performance will also be achievable for the human pilot with decent workload. Consequently, the assessment results can be used to identify CSAS controller’s satisfactory effect domain, and furthermore, in aid of CSAS gain scheduling strategy design.
Research of a High Thermal-noise Test System Based on Progressive Wave Sound Field
Authors: Shen Zhiqiang , Fang Guiqian , Wu Yao , Li Xinming , Zhang Jungang
Published: April 2021

Basing on the existing situation of the thermal source, this paper designed a thermal noise load simulation test system which can make the 1200 mm×1200 mm large panel structure meet the requirement of 165 dB (GJB 150.17 A - 2009) and 1200 °C. This paper introduced the overall design and the design method of the key components. In this paper, the acoustic field uniformity of progressive wave and the acoustic field distribution at the surface of the specimen under high temperature are analyzed by means of numerical simulation. Finally, the developed system was verified by using 1200 mm×1200 mm wallboard structure which led to a stable and good effect.
Shaft friction from the DMT and direct shear interface tests
Authors: Mikina K , Konkol J , Balachowski L
Published: April 2021

The article presents preliminary attempt to create tri-linear transfer curves for describing pile behaviour under axial loading. Transfer curves would use the parameter measured in dilatometer test, particularly a constrained modulus MDMT. The proposed method is based on concrete rough and smooth interface tests performed in a direct shear apparatus. Based on the obtained mobilization curves, relationships were created between the parameters describing the slope of individual transfer curves and the MDMT
modulus. The obtained correlations were used to estimate the capacity of the concrete screw pile subjected to the static load test in tension.
Statistical evaluation of physical and index properties of Vistula Marshlands deltaic soft soils
Authors: Konkol J , Balachowski L
Published: April 2021

This paper provides statistical evaluation of physical and index parameters of the Vistula Marshlands deltaic soft soils using three datasets. Soft soils from the Vistula Marshlands are grouped into the four categories: (1) silty/sandy loams, (2) organic clays, (3) organic silts and (4) peats. Variability of basic and derivative physical properties as well as Atterberg’s limits and plasticity index is studied. It is found that index properties for all soil groups are characterized by large scatter (COV about 50%). The most reliable parameters for silty loams, organic clays and silts are soil density (COV<10%) and specific gravity (COV about 2%). Physical/index parameters of peats are characterized by large scatter, which indicates very local properties and individual formation process. Most of the data points for physical/index quantity are within ±1SD range regardless normality of data distribution. In the main body of this paper, the quantitative physical/index properties variability is evaluated and some practical design guidelines concerning variability of deltaic soil in the Vistula Marshlands are given.
Inspection of open-pit mine drainage characteristics with a horizontal borehole camera
Authors: Perdigâo C , Dyson A , Yaghoubi M , Baumgartl T
Published: April 2021

Horizontal bores and drains are crucial infrastructures for maintaining the stability of large open-pit mines. Induced deformations as the result of mining activities and the infiltration of water from large surface catchments during heavy rain events can cause the build-up of pore water pressures in brown coal batters. This can potentially lead to catastrophic slope failures. Horizontal boreholes and drains are commonly installed at shallow inclines and typically range in length from 150 to 400 metres. Due to complexities in surveying lengthy horizontal bores, the long-term internal properties of these structures are poorly understood. In this research, a specialised horizontal borehole camera was developed to observe a range of factors influencing borehole performance including the identification of fractured or jointed material, borehole geometry and features, and locationally dependent water outflow and drainage paths. Investigations were undertaken at an operational brown coal mine in the Latrobe Valley, located in Victoria, Australia. Features observed on the profile of horizontal bores are discussed, with an emphasis on providing in-situ material characterisation and for the purposes of maintaining stable mine batters.
Determining the subgrade reaction modulus. Mathematical approach on case study
Authors: Nagy A-Cs , Pasca D M , Fàrcas V-S , Zaharia G , Bruchental C
Published: April 2021

Subgrade reaction modulus (k) is the reaction pressure sustained by the soil sample under a rigid plate of standard diameter per unit settlement measured at a specified pressure or settlement. For the design of industrial slabs, the geotechnical engineer should provide two values for the subgrade modulus: the first value will be used for short-term loadings such as lift-truck wheel loads, and the second value will be used for long-term loadings such as uniform storage loads or wide area rack. Unfortunately, there are no direct laboratory procedure in order to determine the value of the subgrade reaction modulus, the only way to determine the value is by field tests or by correlation with other tests. The most common used field test is the plate bearing test. The paper is based on a case study, conducted on a site located in Romania, Maramures county. In order to verify the slab base and to determine the value of k, plate tests according to German norm DIN 18134 were performed on the site of a large logistics center in Baia Mare. Two methods were used for the interpretation of the data from the tests performed on the site. The first method is based on a program designed in Excel, and the second method is based on a program written in Qt Creator, using C++ programming language. At the end a comparison was made between the results obtained with the two use methods. The interpretation procedure presents a series of difficulties based on the form of the resulting function. These issues were addressed in the present study.
Dynamic compaction of crushed concrete fill, full-scale test at Jätkäsaari, Helsinki
Authors: Anttila S , Forsman J , Rantala K , Dettenborn T , Suominen M , Lehtonen J
Published: April 2021

Concrete waste in the form of crushed concrete can be utilized in street and road structures. Today, a significant amount of concrete waste generated by various demolition and other activities is not fully utilized in infrastructure projects within Helsinki; as a result, a portion of concrete waste generated in the city is be transported to other sites outside the Helsinki metropolitan area. In Helsinki, large-scale land reclamation projects have been implemented, and this trend will continue in the near future. Utilization of concrete waste as fill material in land reclamation projects will reduce the need to transport concrete waste outside the Helsinki metropolitan area, with a concurrent reduction in need to transport blasted rock to the land reclamation sites. This will promote reuse and recycling of waste and will reduce heavy traffic and CO2 emissions. Crushed concrete has not been previously tested in Finland as a fill material in land reclamation projects subjected to deep compaction methods. In 2018-2019 suitability of crushed concrete for land reclamation purposes was tested in a full-scale dynamic compaction test. The objective of the test was to assess the degree of compaction produced by dynamic compaction, determine the compression rate of compacted layers under pre-loading embankment, and measure environmental impacts of the fill material. The pilot structure was implemented in Tritoninpuisto (Triton Park) located in the southern part of Jatkasaari. Crushed concrete with varying grain size was compacted using the dynamic compaction method. All materials compacted well. Results of the pilot study indicate that dynamic compaction can be applied to densify crushed concrete fill material for land reclamation. Settlement plates on the top and the bottom of the pilot structure were used to monitor short-term settlement during dynamic compaction and long-term settlement after completion of the work. Long-term settlement was minor after compaction and placement of a pre-loading embankment. Implemented study has indicated that compacted crushed concrete is a suitable material for land reclamation in street and park areas.
A new stress-dilatancy framework for the modelling of rocks and rock masses
Authors: Tsegaye A B
Published: April 2021

It is known that the stress-dilatancy behaviour of soils and rock masses is an integral aspect of their deformation behaviour; and that stress-dilatancy relations for soils and rocks and rock masses have strong similarities. However, when stress-dilatancy relations tuned for soils are directly adopted in constitutive models for rocks and rock masses without due consideration for differences in their yielding characteristics, some unintended assumptions are carried over. This has consequences on the qualitative and quantitative aspects of the predicted stress-strain behaviour. In this paper, a new stress-dilatancy relation tuned towards the modelling of deformation behaviour of rocks and rock masses is presented. The formulation is established in both plane strain and full 3D and accommodates both loading and unloading in shear and effect possible non-coaxiality between eigen directions of plastic strain increments and stresses.
Models for predicting the suction of heaving compacted soils using geotechnical properties
Authors: Fondjo Armand Augustin , Theron Elizabeth , Ray Richard P.
Published: April 2021

Soil suction is the major property that controls the behaviour of unsaturated soils. Suction estimation is challenging both in the lab and the field. Various instruments to measure the suction have been developed with the recent technological advancements. Nonetheless, there are still limitations in regards to the reliability, cost, suction range, accessibility, scope of activity, and appropriateness for use either within the field or lab settings. The filter paper method is probably the simplest procedure to measure the suction for the entire range both in the field and the lab. Nevertheless, the procedure takes time. To alleviate the requirement for conducting this test, it becomes imperative to develop mathematical predictive models for soil suction. In this study, a detailed survey was carried out across the Free State province, South Africa, and sampling points identified. Samples were tested for their geotechnical properties. The influence of the geotechnical properties on soil suction was studied. Multivariate regression analysis was carried out utilizing MINITAB 18 program to develop the mathematical predictive models.
Disruption, innovation, and opportunity with reinforced soil structures
Authors: Hoffman Peter
Published: April 2021

Reinforced soil is an area where amazing opportunity remains. Its failures have been embarrassing and disruptive, even catastrophic, for companies and governments. After reviewing design methods (i.e., limit, stiffness, and granular stability), this paper describes four areas of innovation and opportunity:

• Optimal Stiffness — fiberglass and aramid

• Stabilization of Poor Quality Fills — non-woven geosynthetics

• Friction Connections and Facing Pressure — steel grids

• Strips versus Sheets — geosynthetic strips

The two common construction types (i.e., steel strips, geosynthetic grids or sheets) represent only 25% or two out of eight possibilities discussed. This paper explains why the other six construction types, or 75%, are promising if not better.
Do the standards need modifications? A proposal for geotechnical stability safety factor of breakwater
Authors: Mollaert J , Tavallali A , Maertens J
Published: April 2021

In different countries and continent, different standards are followed for geotechnical stability safety factors of breakwaters which are not exactly in the same line. Parties involved in breakwater design and construction projects might follow different procedures/standards (load cases to be analysed and the acceptable safety factor). It is a fact that a clear table that shows the acceptable safety factors for different load cases is not clearly presented in the standards. So the aim is to provide a proposal that covers all the standards. In this paper, four guidelines/standards of “Rock Manual”, “US Army Corps of Engineers”, “Eurocodes” and “ROM” are reviewed. Based on the mentioned standards and some considerations a table that shows the acceptable safety factors for different load cases is presented. Another concerns is that the actual more powerful and advanced calculation software allows to find the results with less uncertainty compared to the formerly applied methods. It means that lower safety factors in comparison to the old methods can be applied and accepted with the recent software. The aim of the paper is presenting a procedure for the slope stability safety factors in order to reduce the amount of discussions and disagreements that of course come from the interpretations of different standards. Furthermore, reduced slope stability safety factors for different load cases are proposed.
A numerical assessment of jetty side support system
Authors: Elgamal Ahmed
Published: April 2021

Steel sheet piles are amongst the most common kinds of quay walls used in the construction of port and harbor facilities. These are used most often for the birth of small crafts that have limited dimensions and capacity. An increasing number of berths require upgrades because of the growing market in marine traffic around the world, as well as continuously increasing dimensions and vessel capacities. A number of methods can be used to increase the steel sheet pile wall’s load-carrying capacity, including the use of double sheets with intermediate tie rods. This case study aims to evaluate the use of PLAXIS 3D to check system safety and to ensure sufficient capacity to withstand seismic design forces.
Towards the modelling of uplift resistance of skirted offshore mudmat foundations
Authors: Tsegaye A B , Gloppestad J S , Bendzovski R , Giese S
Published: April 2021

A well-planned retrieval or removal operation of deep-water subsea foundations, such as mudmats, resting on soft soil requires estimation of the uplift forces required for the execution of the retrieval. In this paper, mathematical functions that are tuned to describe the uplift resistance due to skirt-soil friction and suction are proposed. Furthermore, possible benefit from inclined pull is deduced.
Detection of Defects in Bored Piles By Non-Destructive Methods On LRT Construction Site
Authors: Zhussupbekov Askar , Shakirova Nurgul
Published: April 2021

This article presents the detection of defects in bored piles with cross-section 1.2÷1.5 m and length 1÷53 m. PIT and Cross-hole Sonic Logging (CSL) methods were used to detect defects in piles. These works were carried out in the city of Nur-Sultan on LRT construction site. Integrity inspections performed after installation are often the most reasonable alternative available to assess the pile quality. This paper discusses the similarities and differences, also advantages and disadvantages. Both Cross-hole Sonic logging and impact echo integrity testing indicated defects in several pile. Subsequent coring confirmed these defects. The results of the two test methods are presented and compared with each other.
Foundations for light structures
Authors: Mets M , Leppik V , Mussatova J
Published: April 2021

Due to developments in soil mechanics, the price of foundations for ordinary structures has decreased to 5 to 10 per cent of the overall price of the building, but it still remains relatively high, sometimes exceeding 30 %. In Estonia, this issue has been relevant for the past years. The first solution was to use wedged piles under agricultural buildings (barns, storage units etc). As a result, the concrete content of foundations decreased 30 to 60 %, and the rate of steel use went up by 50 %. Currently the cooperation between wedged piles and grillage is being researched, with the objective of lowering the price of foundations. ln weak soils, 2-8 m injection piles have been used under private houses, holiday homes and storage structures, but one can save in the cost of foundations that way. Light structures and storage units have often been erected on screw piles (the steel pipe of the pile 100x100x6 filled with concrete, the pile end a steel sheet 15-20 mm thick and (depending on load bearing capacity) 25-60 cm in diameter. These piles can receive pressure as tension and if designed with the cooperation of piles and grillage in mind, the cost of foundations will decrease 50-60%. All of these solutions have been in use in Estonian silt and sands, the screw piles also in weak soils, where they stand on the dense intermediary layers alternating in weak soils.
Advances in Quality Control Methods for Bored Pile and Diaphragm Wall Foundations with Case Histories
Authors: Hannigan P.J. , Piscsalko G.
Published: April 2021

Higher loads on deep foundations and more stringent deep foundation performance requirements have increased the need for improved quality control methods. To satisfy the design intent, the as-built shape, vertical alignment, base cleanliness, cage alignment, concrete cover, and concrete integrity are all important. Several new or improved quality control methods are available to check these considerations on bored pile and diaphragm wall foundations. This paper presents an overview of recent advances in quality control devices along with condensed case histories illustrating their use and project application.
Methadone bioavailability and dose conversion implications with intravenous and enteral administration: A scoping review
Authors: Liu JiTong , Smith Kathryn E , Riker Richard R , Craig Wendy Y , McKelvy Dina J , Kemp Heather D , Nichols Stephanie D , Fraser Gilles L
Published: April 2021

Purpose

Despite its availability for more than 70 years, many details concerning methadone remain contentious, such as the dosing equivalents for intravenous and enteral administration. A scoping review was performed to evaluate whether existing literature on methadone bioavailability in human subjects support the current recommendation that an equivalent enteral dose is twice the intravenous dose.

Methods

A librarian-assisted search of the PubMed and EMBASE databases identified all English-language articles with the terms methadone and bioavailability and/or conversion in the title or abstract published from inception though December 2019. A manual search of references was also performed to identify any additional articles. Studies were included in a scoping review if they were published in English and evaluated methadone bioavailability in human subjects.

Results

Among 65 publications initially identified, 6 studies involving a total of 50 patients were included in the review. Bioavailability data for healthy volunteers and patients with opioid use disorder, metastatic cancer, chronic pain from malignant or nonmalignant disease were available for analysis. The pooled mean (95% confidence interval) bioavailability (F) was 85.4% (75.2%-95.6%), with heterogeneity (I2) of 0. In the 4 studies that provided individual patient–level data, F was >50% in 40 of 42 patient measurements (95.2%) and ≥75% in 33 of 42 patient measurements (78.6%).

Conclusion

Available evidence suggests the bioavailability of methadone is generally more than 75%, there is limited evidence for the currently recommended 1:2 ratio (intravenous:enteral), and a more appropriate dosing ratio may be 1:1.3. This scoping review underscores the need for further research to establish an effective and safe ratio when converting between intravenous and enteral dosing formulations of methadone.
Children’s Knowledge of Multiple Word Meanings: Which Factors Count and For Whom?
Authors: Booton Sophie A , Wonnacott Elizabeth , Hodgkiss Alex , Mathers Sandra , Murphy Victoria A
Published: April 2021

Most common words in English have multiple different meanings, but relatively little is known about why children grasp some meanings better than others. This study aimed to examine how variables at the child-level, wordform-level, and meaning-level impact knowledge of words with multiple meanings. In this study, 174 children aged 5- to 9-years-old completed a test of homonym knowledge, and measures of non-verbal intelligence and language background were collected. Psycholinguistic features of the wordforms tested were assessed through collecting adult ratings, corpus coding, and using existing databases. Logistic mixed effects models revealed that whilst the frequency of wordforms contributed to children’s knowledge, so also did dominance and imageability of the separate meanings of the word. Predictors were similar for children with English as an Additional Language and English as a first language. This greater understanding of why some word meanings are known better than others has significant implications for vocabulary learning.
Discovery of a novel linc01125 isoform in serum exosomes as a promising biomarker for NSCLC diagnosis and survival assessment
Authors: Xian Jianfeng , Zeng Yuyuan , Chen Shizhen , Lu Liming , Liu Li , Chen Jinbin , Rao Boqi , Zhao Zhuxiang , Liu Jun , Xie Chenli , Zhu Lingling , Zhang Duo , Qiu Fuman , Lu Jiachun , Yang Lei
Published: April 2021

A non-invasive method to distinguish potential lung cancer patients would improve lung cancer prevention. We employed the RNA-sequencing analysis to profile serum exosomal long non-coding RNAs (lncRNAs) from non-small cell lung cancer (NSCLC) patients and pneumonia controls, and then determined the diagnostic and prognostic value of a promising lncRNA in four datasets. We identified 90 dysregulated lncRNAs for NSCLC and found the most significant lncRNA was a novel isoform of linc01125. Serum exosomal linc01125 could distinguish NSCLC cases from disease-free and tuberculosis controls, with the area under the curve values as 0.662 [95% confidence interval (CI) = 0.614–0.711] and 0.624 (95% CI = 0.522–0.725), respectively. High expression of exosomal linc01125 was also correlated with an unfavorable overall survival of NSCLC (hazard ratio = 1.48, 95% CI = 1.05–2.08). Clinic treatment decreased serum exosomal linc01125 in NSCLC patients (P = 0.036). Linc01125 functions to inhibit cancer growth and metastasis via acting as a competing endogenous RNA to up-regulate tumor necrosis factor alpha-induced protein 3 (TNFAIP3) expression by sponging miR-19b-3p. Notably, the oncogenic transformation of 16HBE led to decreased linc01125 in cells but increased linc01125 in cell-derived exosomes. The expression of linc01125 in total exosomes was highly correlated with that in tumor-associated exosomes in serum. Moreover, lung cancer cells were capable of releasing linc01125 into exosomes in vitro and in vivo. Our analyses suggest serum exosomal linc01125 as a promising biomarker for non-invasively diagnosing NSCLC and predicting the prognosis of NSCLC.
Alzheimer’s Pathology Is Associated with Dedifferentiation of Intrinsic Functional Memory Networks in Aging
Authors: Cassady Kaitlin E , Adams Jenna N , Chen Xi , Maass Anne , Harrison Theresa M , Landau Susan , Baker Suzanne , Jagust William
Published: April 2021

In presymptomatic Alzheimer’s disease (AD), beta-amyloid plaques (Aβ) and tau tangles accumulate in distinct spatiotemporal patterns within the brain, tracking closely with episodic memory decline. Here, we tested whether age-related changes in the segregation of the brain’s intrinsic functional episodic memory networks—anterior-temporal (AT) and posterior-medial (PM) networks—are associated with the accumulation of Aβ, tau, and memory decline using fMRI and PET. We found that AT and PM networks were less segregated in older than that in younger adults and this reduced specialization was associated with more tau and Aβ in the same regions. The effect of network dedifferentiation on memory depended on the amount of Aβ and tau, with low segregation and pathology associated with better performance at baseline and low segregation and high pathology related to worse performance over time. This pattern suggests a compensation phase followed by a degenerative phase in the early, preclinical phase of AD.
Seroprevalence of Antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 Among Healthcare Workers in Kenya
Authors: Etyang Anthony O , Lucinde Ruth , Karanja Henry , Kalu Catherine , Mugo Daisy , Nyagwange James , Gitonga John , Tuju James , Wanjiku Perpetual , Karani Angela , Mutua Shadrack , Maroko Hosea , Nzomo Eddy , Maitha Eric , Kamuri Evanson , Kaugiria Thuranira , Weru Justus , Ochola Lucy B , Kilimo Nelson , Charo Sande , Emukule Namdala , Moracha Wycliffe , Mukabi David , Okuku Rosemary , Ogutu Monicah , Angujo Barrack , Otiende Mark , Bottomley Christian , Otieno Edward , Ndwiga Leonard , Nyaguara Amek , Voller Shirine , Agoti Charles N , Nokes David James , Ochola-Oyier Lynette Isabella , Aman Rashid , Amoth Patrick , Mwangangi Mercy , Kasera Kadondi , Ng’ang’a Wangari , Adetifa Ifedayo M O , Wangeci Kagucia E , Gallagher Katherine , Uyoga Sophie , Tsofa Benjamin , Barasa Edwine , Bejon Philip , Scott J Anthony G , Agweyu Ambrose , Warimwe George M
Published: April 2021

Background

Few studies have assessed the seroprevalence of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers (HCWs) in Africa. We report findings from a survey among HCWs in 3 counties in Kenya.

Methods

We recruited 684 HCWs from Kilifi (rural), Busia (rural), and Nairobi (urban) counties. The serosurvey was conducted between 30 July and 4 December 2020. We tested for immunoglobulin G antibodies to SARS-CoV-2 spike protein, using enzyme-linked immunosorbent assay. Assay sensitivity and specificity were 92.7 (95% CI, 87.9-96.1) and 99.0% (95% CI, 98.1-99.5), respectively. We adjusted prevalence estimates, using bayesian modeling to account for assay performance.

Results

The crude overall seroprevalence was 19.7% (135 of 684). After adjustment for assay performance, seroprevalence was 20.8% (95% credible interval, 17.5%–24.4%). Seroprevalence varied significantly (P < .001) by site: 43.8% (95% credible interval, 35.8%–52.2%) in Nairobi, 12.6% (8.8%–17.1%) in Busia and 11.5% (7.2%–17.6%) in Kilifi. In a multivariable model controlling for age, sex, and site, professional cadre was not associated with differences in seroprevalence.

Conclusion

These initial data demonstrate a high seroprevalence of antibodies to SARS-CoV-2 among HCWs in Kenya. There was significant variation in seroprevalence by region, but not by cadre.
Personalized teleprehabilitation in elective cardiac surgery: a study protocol of the Digital Cardiac Counselling randomized controlled trial
Authors: Scheenstra Bart , Mohansingh Chanu , Bongers Bart C , Dahmen Sandra , Wouters Yvonne I M S , Lenssen Ton F , Geerlings Phil , Knols Henriette F M , van Kuijk Sander M J , Kimman Merel L , Nieman Maxime , Maessen Jos G , van’t Hof Arnoud W J , Peyman Sardari Nia
Published: April 2021

Aims

Previous research has shown the possibility to use the pre-operative period to improve a patient’s tolerance for surgery. However, there is limited experience with prehabilitation in cardiac surgery. The aim of this study is to evaluate the effect of a comprehensive personalized teleprehabilitation programme on major adverse cardiac events (MACE) in patients scheduled for elective cardiac surgery. Secondary outcomes are post-operative complications, cardiovascular risk factors, quality of life, and cost-effectiveness.

Methods and results

In this single-centre randomized controlled trial, patients are eligible for inclusion when they are ≥18 years of age and cardiac surgery is scheduled at least 8 weeks from informed consent. Participants will be randomized to the teleprehabilitation group or the control group. After a digital baseline screening for perioperative risk factors, patients in the intervention arm can pre-operatively be referred to one or more of the prehabilitation modules (functional exercise training, inspiratory muscle training, psychological support, nutritional support, and/or smoking cessation). The programme is targeted at a duration of at least 6 weeks. It is executed by a multidisciplinary team using (video)calls and supported by a custom-made digital platform. During the pre-operative period, the platform is also used to inform patients about their upcoming surgery and for telemonitoring.

Conclusion

Reducing perioperative risk factors might result in a reduction of MACE, post-operative complications, length of stay, and cardiovascular risk factors, as well as improved quality of life. Cost-effectiveness will be evaluated.
Studying models of balancing selection using phase-type theory
Authors: Zeng Kai , Charlesworth Brian , Hobolth Asger
Published: April 2021

Balancing selection (BLS) is the evolutionary force that maintains high levels of genetic variability in many important genes. To further our understanding of its evolutionary significance, we analyze models with BLS acting on a biallelic locus: an equilibrium model with long-term BLS, a model with long-term BLS and recent changes in population size, and a model of recent BLS. Using phase-type theory, a mathematical tool for analyzing continuous time Markov chains with an absorbing state, we examine how BLS affects polymorphism patterns in linked neutral regions, as summarized by nucleotide diversity, the expected number of segregating sites, the site frequency spectrum, and the level of linkage disequilibrium (LD). Long-term BLS affects polymorphism patterns in a relatively small genomic neighborhood, and such selection targets are easier to detect when the equilibrium frequencies of the selected variants are close to 50%, or when there has been a population size reduction. For a new mutation subject to BLS, its initial increase in frequency in the population causes linked neutral regions to have reduced diversity, an excess of both high and low frequency derived variants, and elevated LD with the selected locus. These patterns are similar to those produced by selective sweeps, but the effects of recent BLS are weaker. Nonetheless, compared to selective sweeps, nonequilibrium polymorphism and LD patterns persist for a much longer period under recent BLS, which may increase the chance of detecting such selection targets. An R package for analyzing these models, among others (e.g., isolation with migration), is available.
Social Participation in Widowhood: Evidence From a 12-Year Panel
Authors: Lim-Soh Jeremy W
Published: April 2021

Objectives

Social participation is important to the quality of life of older adults, especially widows. This is the first study to test whether older widows’ formal and informal social participation rises or declines using multiple panel observations pre- and postbereavement. This article also tests the moderating effects of economic and marital satisfaction, depression, and husband’s illness before death on these trends.

Methods

Seven waves of the Korean Longitudinal Study of Ageing are used to track changes in 4 measures of social participation—meeting and contacting a child, meeting friends, and attending a formal group. A comparison group of married individuals, weighted with coarsened exact matching, controls for age and time trends. Mixed model regressions estimate the effects of widowhood over time.

Results

Social participation shows little change before bereavement and rises significantly after bereavement for all measures. However, frequencies of meeting and contacting a child peak and decline early postbereavement, while meeting friends and attending a group show delayed but long-lasting effects. With regard to moderators, economic and marital satisfaction are positively associated with overall social participation levels but negatively associated with social participation postbereavement.

Discussion

Increased social participation after bereavement underscores the resilience of widows and the social support they receive. However, differences in timing suggest that contact with children is gradually substituted with extrafamilial relationships in the long run. The negative moderating roles of economic and marital satisfaction point to a paradox where seemingly well-off individuals may be more vulnerable to widowhood.
Women as ‘new security actors’ in preventing and countering violent extremism in Mali
Authors: Lorentzen Jenny
Published: April 2021

The frames of counterterrorism and countering violent extremism are increasingly shaping much international engagement in Mali. In this environment, women's contributions are often reduced to their peacemaking potential. This article studies how the UN policy agendas on Women, Peace and Security (WPS) and Preventing and Countering Violent Extremism (P/CVE) are translated in discourses on P/CVE in Mali. It draws on feminist and postcolonial scholarship to develop a framework for analysing how local intermediaries in norm translation engage in ‘discursive practices of re-presentation’ and conducts a discourse analysis of interviews with Malian civil society and government representatives. The analysis finds that a re-presentation of women as security actors, constructed as an extension of their roles as peacemakers, dominates the discourse. I use the term ‘new security actors’ to describe the dominant re-presentation of women that emerges in this context: a woman who will contribute to preventing radicalization and violent extremism by influencing, counselling, and/or informing on her family or community members. ‘New security actors’, however, emerges as a problematic re-presentation of women which emphasizes traditional gender roles and potentially exposes women to risks, and in many ways seem to contradict much of the normative aspirations of the WPS agenda.
How the clinical research community responded to the COVID-19 pandemic: an analysis of the COVID-19 clinical studies in ClinicalTrials.gov
Authors: He Zhe , Erdengasileng Arslan , Luo Xiao , Xing Aiwen , Charness Neil , Bian Jiang
Published: April 2021

Objective

In the past few months, a large number of clinical studies on the novel coronavirus disease (COVID-19) have been initiated worldwide to find effective therapeutics, vaccines, and preventive strategies for COVID-19. In this study, we aim to understand the landscape of COVID-19 clinical research and identify the issues that may cause recruitment difficulty or reduce study generalizability.

Methods

We analyzed 3765 COVID-19 studies registered in the largest public registry—ClinicalTrials.gov, leveraging natural language processing (NLP) and using descriptive, association, and clustering analyses. We first characterized COVID-19 studies by study features such as phase and tested intervention. We then took a deep dive and analyzed their eligibility criteria to understand whether these studies: (1) considered the reported underlying health conditions that may lead to severe illnesses, and (2) excluded older adults, either explicitly or implicitly, which may reduce the generalizability of these studies to the older adults population.

Results

Our analysis included 2295 interventional studies and 1470 observational studies. Most trials did not explicitly exclude older adults with common chronic conditions. However, known risk factors such as diabetes and hypertension were considered by less than 5% of trials based on their trial description. Pregnant women were excluded by 34.9% of the studies.

Conclusions

Most COVID-19 clinical studies included both genders and older adults. However, risk factors such as diabetes, hypertension, and pregnancy were under-represented, likely skewing the population that was sampled. A careful examination of existing COVID-19 studies can inform future COVID-19 trial design towards balanced internal validity and generalizability.
Dietary fiber in a low-protein diet during gestation affects nitrogen excretion in primiparous gilts, with possible influences from the gut microbiota
Authors: Yang Min , Mao Zhengyu , Jiang Xuemei , Cozannet Pierre , Che Lianqiang , Xu Shengyu , Lin Yan , Fang Zhengfeng , Feng Bin , Wang Jianping , Li Jian , Wu De , Zhuo Yong
Published: April 2021

We investigated the effects of dietary fiber (DF) supplementation in normal or low crude protein (CP) diets on reproductive performance and nitrogen (N) utilization in primiparous gilts. In total, 77 Landrace × Yorkshire pregnant gilts were randomly allocated to four dietary treatments in a 2 × 2 factorial design. The groups comprised 1) equal intake of normal CP (12.82% and 0.61% total lysine), 2) low CP (LP) (10.53% and 0.61% total lysine), and 3) with or 4) without DF supplementation (cellulose, inulin, and pectin in a 34:10:1 ratio). A low-protein diet during gestation significantly reduced daily weight gain from days 91 to 110 of pregnancy (−162.5 g/d, P = 0.004). From N balance trials conducted at days 35 to 38, 65 to 68, and 95 to 98 of pregnancy, DF addition increased fecal N excretion at days 65 to 68 (+24.1%) and 95 to 98 (+13.8%) of pregnancy (P < 0.05) but reduced urinary N excretion (P < 0.05), resulting in greater N retention at each gestational stage. DF increased fecal microbial protein levels and excretion during gestation. An LP diet also reduced urinary N excretion at different gestational stages. An in vitro fermentation trial on culture media with nonprotein N urea and ammonium bicarbonate (NH4HCO3) as the only N sources revealed that microbiota derived from feces of gestating gilts fed the high DF diet exhibited a greater capacity to convert nonprotein N to microbial protein. Microbial fecal diversity, as measured by 16S rRNA sequencing, revealed significant changes from DF but not CP diets. Gilts fed an LP diet had a higher number of stillbirths (+0.83 per litter, P = 0.046) and a lower piglet birth weight (1.52 vs. 1.37 kg, P = 0.006), regardless of DF levels. Collectively, DF supplementation to gestation diets shifted N excretion from urine to feces in the form of microbial protein, suggesting that the microbiota had a putative role in controlling N utilization from DF. Additionally, a low-protein diet during gestation negatively affected the litter performance of gilts.
What Causes the Most Stress in Breast Radiology Practice? A Survey of Members of the Society of Breast Imaging
Authors: Parikh Jay R , Sun Jia , Mainiero Martha B
Published: April 2021

Objective

The objective of this study is to determine the major stressors affecting practicing breast radiologists.

Methods

All members of the Society of Breast Imaging within the United States received an email invitation to complete an anonymous survey evaluating stressors that may contribute to physician burnout. Stressors evaluated included pace at work, work–life balance, care of dependents, job security, financial strain, decreasing reimbursement, new regulations, delivering bad news, fear of getting sued, and dealing with difficult patients, radiologists, and administrators.

Results

The overall response rate was 13.5% (312/2308). For those who opened the email, response rate was 24.6% (312/1269). The most prevalent stressors reported were working too fast (222/312, 71.2%), balancing demands of work with personal life (209/312, 70.0%), fear of getting sued (164/312, 52.6%), and dealing with difficult administrators (156/312, 50%). Prevalence of stress related to new regulation requirements, job security, financial strain, decreased reimbursement, dependent care, call, delivering bad news, and dealing with difficult patients, difficult referrers, and difficult radiologists were present in fewer than 50% of respondents.

Conclusion

The most prevalent sources of stress in breast imaging radiologists relate to working too fast and balancing demands of work with time needed for personal life.
ParapanopeDe Man, 1895 (Decapoda: Brachyura: Pilumnoidea: Galenidae): revisited and revised, with descriptions of two new species
Authors: Ng Peter K L , Guinot Danièle
Published: April 2021

The taxonomy of the pilumnoid genus ParapanopeDe Man, 1895 is revisited and two new species are recognised. With a better series of specimens, more differences between the type species, P. euagoraDe Man, 1895 (from Java), and the morphologically similar P. hextii (Alcock, 1898) (from India) are documented. Specimens previously identified as P. euagora from China, Japan, and Korea are here referred to a new species, P. orientalisn. sp.; while others from Malaysia previously assigned to P. cultripes (Alcock, 1898) are here regarded as P. parvan. sp.Parapanope hextii is recorded from Malaysia, Singapore, and Brunei for the first time, while P. siamensis is a new record for China. The identity of the poorly known P. pagenstecheri (Neumann, 1878) from India and its possible conspecificity with P. hextii also discussed. A key to the eight species of Parapanope now recognised is also presented.
Insecticide Resistance Patterns and Mechanisms in Aedes aegypti (Diptera: Culicidae) Populations Across Abidjan, Côte d’Ivoire Reveal Emergent Pyrethroid Resistance
Authors: Konan Lucien Yao , Oumbouke Welbeck Achille , Silué Urbain Garhapié , Coulibaly Ibrahima Zanakoungo , Ziogba Jean-Claude Tokou , N’Guessan Raphael Kouassi , Coulibaly Daouda , Bénié Joseph Bi Vroh , Lenhart Audrey
Published: April 2021

From 2008 to 2017, the city of Abidjan, Côte d’Ivoire experienced several Aedes-borne disease epidemics which required control of the vector mosquito population based on the reduction of larval habitats and insecticidal sprays for adult mosquitoes. This study was undertaken to assess the insecticide susceptibility status of Aedes aegypti (Linnaeus) in the city of Abidjan. Immature Ae. aegypti were sampled from several larval habitats within seven communes of Abidjan and reared to adults. Three to five days old F1 emerged adults were tested for susceptibility using insecticide-impregnated papers and the synergist piperonyl butoxide (PBO) following WHO bioassay guidelines. The results showed that Ae. aegypti populations from Abidjan were resistant to 0.1% propoxur, and 1% fenitrothion, with mortality rates ranging from 0% to 54.2%. Reduced susceptibility (93.4–97.5% mortality) was observed to 0.05% deltamethrin, 0.75% permethrin, 0.05% lambda-cyhalothrin, 5% malathion, and 0.8% chlorpyrifos-methyl. This reduced susceptibility varied depending on the insecticide and the collection site. The restoration of mortality when the mosquitoes were pre-exposed to the synergist PBO suggests that increased activity of oxidases could be contributing to resistance. Three kdr mutations (V410L, V1016I, and F1534C) were present in populations tested, with low frequencies for the Leu410 (0.28) and Ile1016 (0.32) alleles and high frequencies for the Cys1534 allele (0.96). These findings will be used to inform future arbovirus vector control activities in Abidjan.