bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of focus groups in cultural ecosystem services research: a systematic review
Authors: Slovák Ľuboš , Daněk Jan , Daněk Tomáš
Published: February 2023

Focus groups are an increasingly popular method for eliciting non-material values and cultural ecosystem services (CES) in the context of studying human–nature relationships. We conducted a systematic review of the literature with the aim of exploring where and how focus groups were used in the research into CES. Furthermore, we aimed to highlight good practices and potential caveats of the use of the focus groups method with respect to recommendations in methodological literature. We employed an inclusive CES classification framework and observed that focus groups were mostly used to research Recreation, Aesthetics, and Education categories. The review also discovered insufficient reporting and methodological inconsistencies in some of the studies. We provide suggestions for more robust and trustworthy applications of the focus group method, which can advance both research in this field and the implementation of the ecosystem services concept in the future.
Training future primary teachers in historical thinking through error-based learning and learning analytics
Authors: Tirado-Olivares Sergio , Cózar-Gutiérrez Ramón , López-Fernández Carlota , González-Calero José Antonio
Published: February 2023

Current pedagogical trends move towards the implementation of active methodologies; however, little research has been conducted in the field of history teaching. Purely memorised learning no longer has a place in today’s age of information and technology. Simulating the role of historians in the classroom, what is known as promoting historical thinking, makes more sense. Thus, training teachers on how to develop historical thinking by active methodologies such as error-based learning (EBL) becomes necessary. Moreover, the traditional summative test does not demonstrate the assessment of the level of historical thinking. Nevertheless, technology enables formative assessment by different techniques and tools such as learning analytics (LA). Then, to analyse the potential of combining EBL and LA to foster and evaluate historical thinking can be interesting. To this end, in the present quantitative quasi-experimental study, the impact of EBL and LA to encourage and assess historical thinking skills have been analysed with 107 pre-service teachers. To this end, while 66 students worked with EBL with sources where errors were introduced in a controlled way, the other 41 students worked with the same unmodified sources. At the end of each session, LA was used to analyse the students’ level of knowledge in the six dimensions of historical thinking through interactive questionnaires. The results obtained show an improvement in the historical thinking of future teachers due to the use of EBL. Furthermore, it has been proven that the data obtained from the LA enables predicting the results obtained by the students in a later test. In this way, the usefulness of active methodologies such as EBL combined with LA in the training of future teachers in our area of knowledge contrasts with the methods currently used.
Uniform attractors for nonclassical diffusion equations with perturbed parameter and memory
Authors: Xie Yongqin , Liu Di , Zhang Jiangwei , Liu Ximeng
Published: February 2023

In this paper, we consider the long-time behavior of the nonclassical diffusion equation with perturbed parameter and memory on a bounded domain Ω⊂Rn(n≥3). The main feature of this model is that the equation contains a dissipative term with perturbation parameters −νΔu and the nonlinearity f satisfies the polynomial growth of arbitrary order. By using the nonclassical operator method and a new analytical method (or technique) (Lemma 2.7), the existence and regularity of uniform attractors generated for this equation are proved. Furthermore, we also get the upper semicontinuity of the uniform attractors when the perturbed parameter ν → 0. It is remarkable that if ν = 0, we can get the same conclusion as in the works of Toan et al. [Acta Appl. Math. 170, 789–822 (2020)] and Conti et al. [Commun. Pure Appl. Anal. 19, 2035–2050 (2020)], but the nonlinearity is critical.
Highly stretchable and sensitive silicone composites with positive piezoconductivity using nickel powder and ionic liquid
Authors: Matsuda R. , Isano Y. , Ueno K. , Ota H.
Published: February 2023

Conductive rubber composites are mixtures of stretchable rubber and conductive materials. They can achieve conductivity and high elasticity and are used in soft robots and wearable devices. In general, these composites exhibit high electrical resistance owing to their bonds between the fillers breaking during elongation. However, there are several types of composite materials that decrease resistance by increasing contact between the conductive materials during elongation through optimization of the shape and size of the filler. These composite materials can rapidly decrease the resistance and are expected to be applicable to switch in electric circuits and sensors. However, to use such composite materials in circuits, the electrical resistance at the time of resistance reduction must be sufficiently low to not affect the electric circuit. To achieve this, a considerable amount of filler must be mixed; however, this reduces the elasticity of the composite. Simultaneously achieving elasticity of the composite and a sufficient decrease in the resistance is challenging. This study developed a conductive rubber composite gel by mixing silicone rubber, ionic liquid, and metal filler. Consequently, the composite achieved an elongation rate of over six times and a decrease in the resistance of less than 1/105. In addition, this composite material was used as a switch circuit wherein an electric circuit is turned on and off according to elongation through a connection to a DC power source.
Simulation investigations of a novel L-band metamaterial relativistic oscillator with higher power and lower guiding magnetic field
Authors: Pi Mingyao , He Juntao , Ling Junpu , He Yufang , Zeng Fanbo , Xu Weili
Published: February 2023

In this paper, a novel high-efficiency L-band Metamaterial Relativistic Oscillator (MRO) with high input and output power under relatively low guiding magnetic field has been proposed. In order to increase the power level while decreasing the guiding magnetic field, through our theoretical and simulation investigations on previously designed metamaterial (MTM) structure, we found that the thickness of the ring and the length of the drift tube are the two key factors that can improve the power handling capacity of the MTM structure and field uniformity. Through transmission analysis and electron conductance calculation of the novel MRO based on the improved MTM structure, preliminary MRO design is done. Within CST particle simulation of the proposed MRO and after optimizations, we computationally got a pure 718 MW TE10 output signal at 1.49 GHz using a pulsed electron beam with energy of 700 keV and current of 2 kA under 1 T guiding magnetic field, and the corresponding conversion efficiency is 51.3%. Relevant results of particle simulation verified the previous high frequency analysis. A comparison between our proposed MRO and the previous one reveals that while keeping the high efficiency and miniaturization merits of MRO, the power handling capacity has been increased and the novel MRO works more stable under low guiding magnetic field.
Simultaneous density and thermal conductivity depth profile reconstructions from noised thermal-wave amplitude and phase data using a combined integral-equation and imperialist competitive algorithm method
Authors: Mandelis A. , Kooshki S. , Melnikov A.
Published: February 2023

An efficient new thermal-wave inverse-problem approach based on an integral-equation boundary-value method coupled with an imperialist competitive algorithm was developed. The methodology was successfully applied to simultaneously reconstruct density and thermal conductivity depth profiles in a sintered powder metallurgy sample from an industrial automotive manufacturer with a surface layer of higher density than the bulk. The density and thermal conductivity depth profiles were validated independently using the manufacturer's data and in-house temperature and porosity measurements. The present non-destructive inverse problem approach represents a generalized formalism to thermal-wave reconstruction of dual depth profiles using frequency scan data measured from the interrogated surface. From a fundamental viewpoint, the method adds significant insights into the relationship between thermal conductivity and density distributions in inhomogeneous solids.
Computational analysis of electrical breakdown of SF6/N2 mixtures
Authors: Levko Dmitry , Raja Laxminarayan L.
Published: February 2023

The main aim of the present paper is to clarify the influence of the SF6 fraction in the SF6/N2 mixture on the breakdown voltage. For this, the two-dimensional axisymmetric fluid model coupled with the comprehensive mechanism of plasma chemical reactions is used. In addition, the influence of various parameters such as the voltage rise time and the SF6 fraction in the mixture is analyzed. It is observed that depending on the voltage rise time an admixture of only 1% of SF6 to N2 results in an increase in the breakdown voltage by 7%–43%. The sensitivity of breakdown voltage decreases with decreasing voltage rise time and is caused by the electron attachment time scale becoming comparable to the breakdown time. The results of simulations confirm that the increase in the SF6 fraction in the mixture leads to an increase in the breakdown voltage. This is explained by the influence of the SF6 fraction on the electron attachment rate coefficients rather than on the ionization reactions.
An iterative polygonal micromagnet design for spin–photon coupling on silicon
Authors: Yang Jie-Cheng , Li Zong-Hu , Wang Bao-Chuan , Li Hai-Ou , Cao Gang , Guo Guo-Ping
Published: February 2023

Research to realize full electrical spin manipulation and spin–photon coupling on silicon using micromagnets has been prevalent. To realize spin–photon coupling, micromagnets should be placed parallel to the double quantum dot connection direction. However, the parallelly placed micromagnet will also generate detrimental magnetic field gradients, which results in substantial dephasing of the qubit [Yoneda et al., Nat. Nanotechnol. 13, 102–106 (2018); Struck et al., npj Quantum Inf. 6(1), 40 (2020); Takeda et al., Nat. Nanotechnol. 16, 965–969 (2021)]. Here, we develop a scheme of an iterative polygonal micromagnet, which maximizes the qubit Rabi oscillation quality factor [Takeda et al., Sci. Adv. 2, e1600694 (2016)] Q, while allowing strong spin–photon coupling. To find the optimal structure of the micromagnet in the iterative process, the appropriate objective function R (proportional to 1/Q) is selected as the evaluation standard of micromagnet performance. The simulation results by the RADIA package show that the Q value of the polygonal micromagnet is 15% better than that of the rectangular micromagnet at most and up to approximately 30% in subsequent simulation using the OOMMF tool.
Memory association circuit based on memristor for neural networks
Authors: Chen Yulong , Li Lei , Wang Nuo , Wang Hongyu , Yang Zheming , Long Dingyu
Published: February 2023

Memristors have been favored in artificial intelligence, neural networks, and chaotic circuits, especially in neural synapses because of their unique advantages such as resistance variability, nonvolatile nature, and nanometer size. Benefits such as integration scale and low power consumption contribute toward simulating the biological synaptic function. Compared with memory association circuits using traditional CMOS transistors, memristors will reduce the complexity of the circuit and the power consumption. Therefore, it is greatly promising to use memristors as synapses to construct neural networks to mimic human brain functions. This paper successfully establishes a recognition circuit based on memristors to recognize some characteristics (size, color, shape, and smooth) of fruits, which is a learning function. After a few seconds, the output signal voltage drops, and this is a forgetting function. Through the establishment of a recognition circuit, the neural network and human complex behavior were simulated. This work lays the foundation for further research of human neural networks.
Research on transient composition tracking in natural gas condensate pipeline networks
Authors: Song Shangfei , Fan Di , Fan Yijia , Yan Bing , Shi Bohui , Zhang Shengnan , Lv Xiaofang , Yao Haiyuan , Li Qingping , Gong Jing
Published: February 2023

Offshore pipelines are hailed as the “lifeline” of an offshore oil and gas production system and are essential for offshore oil and gas development. Component tracing technologies for the oil and gas multiphase transmission pipeline networks need to be urgently developed to predict the fluid composition changes in pipeline networks. Instead of assuming the fluid components are constant, we consider they varied with flow. The component conservation equations and a phase change model are established. The equation of state of the fluid is adopted to determine the equilibrium state of each component in real time. Considering the macroscopic flow calculation, microscopic fluid components, and phase equilibrium, the component tracking algorithm is established for natural gas condensate pipeline networks, which can dynamically track the fluid composition in pipeline networks and calculate the phase exchange amount and related flow parameters in real time. Three case studies are performed to verify the effectiveness of the algorithm. These findings are of great practical significance for understanding the gas–liquid two-phase flow in pipeline networks, promoting further engineering applications of component tracking on pipeline networks.
Pore-scale investigation on the effect of icing on relative permeability of two-phase immiscible fluids
Authors: Zhang Da , Li Yan , Mei Ning , Yuan Han , Shu Chang
Published: February 2023

In this study, the flow behavior and relative permeability (kr) curve of the immiscible two-phase flow accompanied by icing in a horizontal channel were studied using the lattice Boltzmann method-phase field method (LBM-PFM) coupling model at the pore-scale. A novel LBM-PFM coupled model is proposed and tested by comparison with analytical and experimental results, and good agreement is achieved in general. Then, the model is used for simulating two-phase fluids (brine water–oil) flow during icing. In addition, the effects of initial phase distribution, capillary number, and heat flux are numerically discussed. The results show that, the distribution characteristics of the relative permeability curves of the immiscible fluids during the crystallization process are determined by the initial phase distribution. The Ca number is a positive correlation function of kr, while the kr curve is not sensitive to the change of heat flux.
Maximum energy product of exchange-coupled Sm(FeCo)12/α-Fe nanocomposite particle
Authors: Uda Ryusei , Koike Kunihiro , Inaba Nobuyuki , Kato Hiroaki , Itakura Masaru , Okubo Susumu , Ohta Hitoshi , Tsuchiura Hiroki
Published: February 2023

The effects of the coating surface orientation of the α-Fe soft magnetic layer on the Sm(Fe0.8Co0.2)12 hard magnetic phase and the volume fraction of α-Fe, VFe, on the maximum energy product, (BH)max of exchange-coupled Sm(Fe0.8Co0.2)12/α-Fe nanocomposite magnet particles were micromagnetics OOMMF package was systematically investigated. The (BH)max of the reference model, Sm(Fe0.8Co0.2)12 particles without Fe layer, was 630 kJ/m3. In contrast, in the nanocomposite magnet particle model with soft magnetic layers on both sides of the hard magnetic phase, (BH)max reached a maximum value of 657 kJ/m3 at VFe = 12% (Fe layer thickness, tFe = 2 nm). In the model with α-Fe coating on the top and bottom surfaces of the hard magnetic phase, (BH)max = 636 kJ/m3 at VFe = 4% (tFe = 2 nm). Furthermore, the coating of the soft magnetic phase on both sides of the hard phase particles reduces the magnitude of the demagnetizing field, Hd of the nanocomposite magnet particles, indicating that the side coating of the soft magnetic phase is effective in increasing (BH)max. These findings allow for a greater degree of freedom in the design of nanocomposite magnets by adjusting not only the VFe volume fraction of the hard/soft phases but also their arrangement.
Synthesis and characterization of Craig-type antiaromatic species with [4
n
+ 2] π electrons
Authors: Chen Lina , Lin Lu , Nath Amit Ranjan , Zhu Qin , Chen Zhixin , Wu Jingjing , Wang Hongjian , Li Qian , Lin Wen-Feng , Zhu Jun , Xia Haiping
Published: February 2023

Antiaromaticity is extended from aromaticity as a complement to describe the unsaturated cyclic molecules with antiaromatic destabilization. To prepare antiaromatic species is a particularly challenging goal in synthetic chemistry because of the thermodynamic instability of such molecules. Among that, both Hückel and Möbius antiaromatic species have been reported, whereas the Craig one has not been realized to date. Here, we report the first example of planar Craig antiaromatic species. Eight Craig antiaromatic compounds were synthesized by deprotonation-induced reduction process and were fully characterized as follows. Single-crystal X-ray crystallography showed that these complexes have planar structures composed of fused five-membered rings with clearly alternating carbon–carbon bond lengths. In addition, proton NMR (
1
H NMR) spectroscopy in these structures showed distinctive upfield shifts of the proton peaks to the range of antiaromatic peripheral hydrogens. Experimental spectroscopy observations, along with density-functional theory (DFT) calculations, provided evidence for the Craig antiaromaticity of these complexes. Further study experimentally and theoretically revealed that the strong exothermicity of the acid-base neutralization process was the driving force for this challenging transformation forming Craig antiaromatic species. Our findings complete a full cycle of aromatic chemistry, opening an avenue for the development of new class of antiaromatic systems.
An Exploratory Evaluation of the Impact and Acceptability of a Structured Reflective Practice Program Piloted with Staff in a Forensic Mental Health Setting
Authors: Aurora Meera , Mawren Daveena , Fullam Rachael
Published: February 2023

This study describes and examines the impact of a novel Reflective Practice program tailored to the multidisciplinary clinical workforce at an inpatient forensic mental health setting. Surveys assessing wellbeing, self-efficacy and reflective practice capacity were administered to all clinical staff prior to commencement of the Reflective Practice program, as well as six months post-implementation. Interviews were also conducted with key clinical stakeholders to obtain detailed feedback regarding the impact of the program across the organization following six-eight months of implementation. Staff who participated in post-implementation surveys reported significantly higher confidence in their work when compared to staff at baseline, while clinical stakeholders observed improvements in the cohesion of the multidisciplinary team. In spite of the limitations of the pragmatic study design and small sample size, results suggest the novel Reflective Practice program offers an acceptable model for adoption in an inpatient forensic mental health setting, with potential to improve the wellbeing, learning and morale of a forensic mental health workforce. The findings also highlight the need to support practice development and wellbeing in early career clinicians, where low confidence and high stress are predominant.
Experimental study on friction-assisted electroforming of Ni-Co alloys
Authors: Zhang Yong , Qian Shuang-Qing , Fu Xin-Feng
Published: February 2023

Owing to the complexity of the electroforming mechanism, the structure of electroformed deposits is affected by many process parameters, and defects such as pinholes and nodules in electroformed deposits must be solved. In this study, the mechanism by which hard particles inhibit the formation of the above defects in the electroforming process of Ni-Co alloys was analyzed. Through the friction-assisted electroforming Ni-Co alloy tests, the effects of friction and current density on the hardness, texture and microstructure of the Ni-Co electroformed deposits were studied. The results show that the microhardness of the Ni-Co coatings obtained is between 651 HV and 669 HV with the increase of the cathode speed from 8 rpm to 512 rpm. When the cathode speed is 16rpm, the grain sizes of Ni-Co coatings increase with the increase of cathode current density from 2 A dm−2 to 8 A dm−2, and the microhardness of the coatings is between 672 HV and 590 HV.
Impact of fine particulate matter and toxic gases on the health of school children in Dhaka, Bangladesh
Authors: Roy Shatabdi , Zaman Shahid Uz , Joy Khaled Shaifullah , Jeba Farah , Kumar Prashant , Salam Abdus
Published: February 2023

Background. Air pollution exposure has a detrimental effect on children who spend more than 17% of their weekdays inside a school building. The purpose of this study is to look into the effects of particulate matter (PM) and toxic gases on health of the school children. Between April and November 2018, samples were collected in real time from ten different schools (both indoor and outdoor) over four hours on two consecutive days at each school. During the first two hours, when students were present in the classroom, measurements were conducted inside the classroom. After that the measurements were conducted outside the classroom but within the school premises - when students were playing on the playground or eating breakfast outside of classroom. Method. To evaluate the impact of air pollution, 250 students (on average 20 students from each school) aged from 9 to 12 were selected from ten schools. Automatic monitors (AEROCET 531S, USA) were employed to measure PM1.0, PM2.5, and PM10 concentrations. NO2, TVOC, and CO2 concentrations were measured using an AEROQUAL (500S, New Zealand), and the respiratory rate is measured by BSMI Peak Flow Meter (Made: BSMI, Origin: China). Monitors were placed at about 2.0 meters above the floor at breathing height and no student wore the sensors. The ANOVA test was conducted to see the statistical significance between air quality parameters and peak flow meter readings. Results. The mean ± standard deviation of PM1.0, PM2.5, and PM10 concentrations were 19.1 ± 3.6, 34.2 ± 10.1, and 131.3 ± 58.6 μgm−3, respectively. PM2.5 and PM10 concentrations exceeded WHO standards (15 and 45 μgm−3 of 24 h) by 2.3 and 2.9 times. The highest concentrations of toxic gases were found on school campuses where vehicle densities (measured manually) were high. The mean Hazard Quotient (HQ) for PM10 (2.5 ± 2.2 indoor; 3.6 ± 2.6 outdoor) and PM2.5 (1.8 ± 0.8 indoor; 1.9 ± 1.0 outdoor) among all participating students was >1 indicating an unacceptable risk for human health. Lung function associated with the PEF value has a negative correlation with PM1.0 and PM2.5 concentrations in most cases. Conclusions. The findings of this study are useful in gaining a general understanding of the school environment in Dhaka. It aimed to understand how children were personally exposed in school and to develop effective control strategies to mitigate negative effects.
Enhancement of CO2RR product formation on Cu-ZnO-based electrodes by varying ink formulation and post-treatment methods
Authors: Jaster Theresa , Albers Simon , Leonhard Armin , Kräenbring Mena-Alexander , Lohmann Heiko , Zeidler-Fandrich Barbara , Özcan Fatih , Segets Doris , Apfel Ulf-Peter
Published: February 2023

Numerous catalysts have been reported with enhanced performance, e.g. longer lifetime and improved selectivity, for the electrochemical CO2 reduction reaction (CO2RR). Respectively little is, however, known about the influence of the electrode structuring and pre-treatment on this reaction for catalytic layers. Thus, we herein report on the modification of the catalyst environment of a Cu-ZnO-carbon black catalyst by variation of the ink composition and subsequent electrode treatment before performing CO2RR. We furthermore provide insight into the impact of different solvents, ionomer, and additives like pore forming agents used for the ink preparation as well as post-treatment steps in terms of pressing and sintering of the generated electrodes on the CO2RR performance. Although using the same catalyst for all electrodes, remarkable differences in hydrophobicity, surface morphology, and electrochemical performance with respect to stability and product distribution were observed. Our study reveals the critical role of the catalytic layer assembly aside from using proper catalysts. We furthermore show that the parasitic hydrogen formation and flooding behavior can be lowered and C2+ product formation can be enhanced when operating in optimized gas diffusion electrodes.
A review on metallurgical features of hot-dip aluminized steel
Authors: Dey Partha Pratim , Sahu Shrishty , Banerjee Partha Sakha , Ghosh Manojit
Published: February 2023

Among the various surface modification processes, the hot-dip aluminizing process has increasingly evoked considerable attention. This method has proved to be commercially cost-effective and technically better than galvanizing. In contrast to hot-dip aluminized steel components, galvanized components cannot be used in service conditions at elevated temperatures. During the last few years, intensive research by researchers has yielded new insights into metallurgical aspects of aluminized coating in as-dipped and annealed condition. The present review gives a bird’s eye view of the hot-dip aluminizing process, from the early years of its inception to the current research on aspects of the aluminized coating. The progress of research on thermodynamic studies, phase equilibria, phase identification, and their crystallographic features have been traced in this attempt. This review is not restricted to briefing the research performed so far but also points out several issues of discrepancies among the results of the published literature. Special emphasis has been given to the phase development in the coating during annealing and the increasing horizon of application of hot-dip aluminizing to alloy steels in hot stamped conditions. Reference has also been made to state-of-the-art topics embracing the current research on computer simulation software and sophisticated experimental techniques. However, lower surface hardness and economy restrict the wide application of the hot-dipping process.
A numerical model for diesel engine SCR systems under different inlet NH3 distribution profiles
Authors: d’Apolito Luigi , Hong Hanchi
Published: February 2023

Selective Catalytic Reduction (SCR) technology is currently used to effectively reduce NOx emissions for diesel engines. The present study aims at building a three-dimensional numerical model to evaluate the NOx conversion efficiency and the NH3 slip in an SCR system, reducing the time and resources necessary for design and development process. A numerical model of an SCR system has been built to integrate species transport, heat transfer and flow characteristics along with kinetics of the chemical reactions. In order to systematically simulate situations where the concentration of NH3 at the inlet is not uniform, different NH3 inlet profiles have been built by using a Multivariate Gaussian Distribution and considering the maximum concentration in different locations. The effect of different geometries and NH3 distribution profiles on the NOx conversion efficiency and NH3 slip has been studied. The behaviour of the system at different inlet temperatures has been explored and the reaction rates in the monolith have been analysed. The study has been extended by studying the effect of different NH3/NO ratios to provide a more complete comparison between different designs. The numerical model has been found useful to take into account many aftertreatment system parameters during the design of an SCR system, maximize the NOx conversion efficiency by modifying the NH3/NO ratio while minimizing the NH3 slip, providing a comprehensive tool for the optimization of geometrical characteristics of an SCR system.
Effect of concentration and heat inputs on thermal conductvity of SiC/oil nanofluids
Authors: Srinivas T , Srinivas G
Published: February 2023

The most significant physical property responsible for heat transfer is thermal conductivity. The fluids’ thermal conductivity is improved by the addition of nano powder with better thermal conductivity, which raises the fluid’s coefficient of heat transfer. So far, there is no detailed description of the SiC nanofluid thermal conductance investigation using different base fluids (Engine, Furnace and Transformer Oils) in the literature. The primary objective of in this analysis is to evaluate SiCnan nanofluid’s thermal conductivity in various basefluids (engine oil, furnace oil and transforming oil). The tests were conducted at various temperatures of 30 °C, 35 °C, 40 °C, 45 °C, 50 °C and 55 °C on nanofluid with specific volume fraction concentrations of 0.25, 0.5, 0.75, 1.2, 1.5, 1.75 and 2. The findings showed that the thermal conductivity boosted with the rise in concentration and temperature of SiC/Engine Oil, SiC/Furnace Oil, and SiC/Transformer Oil.
Central limit theorem for the principal eigenvalue and eigenvector of Chung–Lu random graphs
Authors: Dionigi Pierfrancesco , Garlaschelli Diego , Subhra Hazra Rajat , den Hollander Frank , Mandjes Michel
Published: February 2023

A Chung–Lu random graph is an inhomogeneous Erdős–Rényi random graph in which vertices are assigned average degrees, and pairs of vertices are connected by an edge with a probability that is proportional to the product of their average degrees, independently for different edges. We derive a central limit theorem for the principal eigenvalue and the components of the principal eigenvector of the adjacency matrix of a Chung–Lu random graph. Our derivation requires certain assumptions on the average degrees that guarantee connectivity, sparsity and bounded inhomogeneity of the graph.
Hardware optimization for photonic time-delay reservoir computer dynamics
Authors: Zhang Meng , Liang Zhizhuo , Huang Z Rena
Published: February 2023

Reservoir computing (RC) is one kind of neuromorphic computing mainly applied to process sequential data such as time-dependent signals. In this paper, the bifurcation diagram of a photonic time-delay RC system is thoroughly studied, and a method of bifurcation dynamics guided hardware hyperparameter optimization is presented. The time-evolution equation expressed by the photonic hardware parameters is established while the intrinsic dynamics of the photonic RC system is quantitively studied. Bifurcation dynamics based hyperparameter optimization offers a simple yet effective approach in hardware setting optimization that aims to reduce the complexity and time in hardware adjustment. Three benchmark tasks, nonlinear channel equalization (NCE), nonlinear auto regressive moving average with 10th order time lag (NARMA10) and Santa Fe laser time-series prediction tasks are implemented on the photonic delay-line RC using bifurcation dynamics guided hardware optimization. The experimental results of these benchmark tasks achieved overall good agreement with the simulated bifurcation dynamics modeling results.
Log-optimal (𝑑+2)-configurations in 𝑑–dimensions
Authors: Dragnev Peter , Musin Oleg
Published: February 2023

We enumerate and classify all stationary logarithmic configurations of

d
+
2

d+2

points on the unit sphere in

d
d

–dimensions. In particular, we show that the logarithmic energy attains its local minima at configurations that consist of two orthogonal to each other regular simplexes of cardinality

m
m

and

n
n

. The global minimum occurs when

m
=
n

m=n

if

d
d

is even and

m
=
n
+
1

m=n+1

otherwise. This characterizes a new class of configurations that minimize the logarithmic energy on

S

d
−
1

\mathbb {S}^{d-1}

for all

d
d

. The other two classes known in the literature, the regular simplex (

d
+
1

d+1

points on

S

d
−
1

\mathbb {S}^{d-1}

) and the cross-polytope (

2
d

2d

points on

S

d
−
1

\mathbb {S}^{d-1}

), are both universally optimal configurations.
Normal measures on large cardinals
Authors: Apter Arthur , Cummings James
Published: February 2023

The space of normal measures on a measurable cardinal is naturally ordered by the Mitchell ordering. In the first part of this paper we show that the Mitchell ordering can be linear on a strong cardinal where the Generalised Continuum Hypothesis fails. In the second part we show that a supercompact cardinal at which the Generalised Continuum Hypothesis fails may carry a very large number of normal measures of Mitchell order zero.
On unit signatures and narrow class groups of odd degree abelian number fields
Authors: Breen Benjamin , Varma Ila , Voight John
Published: February 2023

For an abelian number field of odd degree, we study the structure of its

2
2

-Selmer group as a bilinear space and as a Galois module. We prove structural results and make predictions for the distribution of unit signature ranks and narrow class groups in families where the degree and Galois group are fixed.
An 8-dimensional family of simply connected Godeaux surfaces
Authors: Schreyer Frank-Olaf , Stenger Isabel
Published: February 2023

In this paper we describe a construction method for numerical Godeaux surfaces based on homological algebra. We show the existence of an 8-dimensional locally complete family of simply connected numerical Godeaux surfaces.
Women's representation in clinical trials of patients with chronic kidney disease
Authors: Pinho-Gomes Ana-Catarina , Carcel Cheryl , Woodward Mark , Hockham Carinna
Published: February 2023

Background

Sex and gender differences in chronic kidney disease (CKD), including epidemiology and response to treatment, remain poorly understood. This study aimed to investigate how women are represented in CKD clinical trials and whether sex- and gender-disaggregated outcomes were reported.

Methods

Clinical trials on CKD were identified from ClinicalTrials.gov. Randomised, phase 3/4 trials with ≥100 participants were selected to quantify women's representation among participants by computing the participation:prevalence ratio (PPR) and investigating whether sex-disaggregated analyses had been performed.

Results

In total, 192 CKD trials registered on ClinicalTrials.gov and published between 1995 and 2022 were included. Overall, women accounted for 66 875 (45%) of the 147 136 participants. Women's participation in clinical trials was lower than their representation in the underlying CKD population globally (55%). The PPR was 0.75 (95% confidence interval 0.72–0.78), with no significant variation irrespective of mean age, CKD stage, dialysis, location, type of intervention or funding agency. A total of 39 (20%) trials reported sex-disaggregated efficacy outcomes and none reported sex-disaggregated safety outcomes.

Conclusion

Women's participation in CKD clinical trials was lower than their representation in the underlying CKD population. Sex-disaggregated efficacy and safety outcomes were rarely reported. Improving women's enrolment into clinical trials is crucial to enable sex- and gender-disaggregated analysis and thus identify potential differences in treatment response between women and men.
Automatic Extraction of Medication Mentions from Tweets—Overview of the BioCreative VII Shared Task 3 Competition
Authors: Weissenbacher Davy , O’Connor Karen , Rawal Siddharth , Zhang Yu , Tsai Richard Tzong-Han , Miller Timothy , Xu Dongfang , Anderson Carol , Liu Bo , Han Qing , Zhang Jinfeng , Kulev Igor , Köprü Berkay , Rodriguez-Esteban Raul , Ozkirimli Elif , Ayach Ammer , Roller Roland , Piccolo Stephen , Han Peijin , Vydiswaran V G Vinod , Tekumalla Ramya , Banda Juan M , Bagherzadeh Parsa , Bergler Sabine , Silva João F , Almeida Tiago , Martinez Paloma , Rivera-Zavala Renzo , Wang Chen-Kai , Dai Hong-Jie , Alberto Robles Hernandez Luis , Gonzalez-Hernandez Graciela
Published: February 2023

This study presents the outcomes of the shared task competition BioCreative VII (Task 3) focusing on the extraction of medication names from a Twitter user’s publicly available tweets (the user’s ‘timeline’). In general, detecting health-related tweets is notoriously challenging for natural language processing tools. The main challenge, aside from the informality of the language used, is that people tweet about any and all topics, and most of their tweets are not related to health. Thus, finding those tweets in a user’s timeline that mention specific health-related concepts such as medications requires addressing extreme imbalance. Task 3 called for detecting tweets in a user’s timeline that mentions a medication name and, for each detected mention, extracting its span. The organizers made available a corpus consisting of 182 049 tweets publicly posted by 212 Twitter users with all medication mentions manually annotated. The corpus exhibits the natural distribution of positive tweets, with only 442 tweets (0.2%) mentioning a medication. This task was an opportunity for participants to evaluate methods that are robust to class imbalance beyond the simple lexical match. A total of 65 teams registered, and 16 teams submitted a system run. This study summarizes the corpus created by the organizers and the approaches taken by the participating teams for this challenge. The corpus is freely available at https://biocreative.bioinformatics.udel.edu/tasks/biocreative-vii/track-3/. The methods and the results of the competing systems are analyzed with a focus on the approaches taken for learning from class-imbalanced data.
Machine learning identifies pathophysiologically and prognostically informative phenotypes among patients with mitral regurgitation undergoing transcatheter edge-to-edge repair
Authors: Trenkwalder Teresa , Lachmann Mark , Stolz Lukas , Fortmeier Vera , Covarrubias Héctor Alfonso Alvarez , Rippen Elena , Schürmann Friederike , Presch Antonia , von Scheidt Moritz , Ruff Celine , Hesse Amelie , Gerçek Muhammed , Mayr N Patrick , Ott Ilka , Schuster Tibor , Harmsen Gerhard , Yuasa Shinsuke , Kufner Sebastian , Hoppmann Petra , Kupatt Christian , Schunkert Heribert , Kastrati Adnan , Laugwitz Karl-Ludwig , Rudolph Volker , Joner Michael , Hausleiter Jörg , Xhepa Erion
Published: February 2023

Aims

Patients with mitral regurgitation (MR) present with considerable heterogeneity in cardiac damage depending on underlying aetiology, disease progression, and comorbidities. This study aims to capture their cardiopulmonary complexity by employing a machine-learning (ML)-based phenotyping approach.

Methods and results

Data were obtained from 1426 patients undergoing mitral valve transcatheter edge-to-edge repair (MV TEER) for MR. The ML model was developed using 609 patients (derivation cohort) and validated on 817 patients from two external institutions. Phenotyping was based on echocardiographic data, and ML-derived phenotypes were correlated with 5-year outcomes. Unsupervised agglomerative clustering revealed four phenotypes among the derivation cohort: Cluster 1 showed preserved left ventricular ejection fraction (LVEF; 56.5 ± 7.79%) and regular left ventricular end-systolic diameter (LVESD; 35.2 ± 7.52 mm); 5-year survival in Cluster 1, hereinafter serving as a reference, was 60.9%. Cluster 2 presented with preserved LVEF (55.7 ± 7.82%) but showed the largest mitral valve effective regurgitant orifice area (0.623 ± 0.360 cm2) and highest systolic pulmonary artery pressures (68.4 ± 16.2 mmHg); 5-year survival ranged at 43.7% (P-value: 0.032). Cluster 3 was characterized by impaired LVEF (31.0 ± 10.4%) and enlarged LVESD (53.2 ± 10.9 mm); 5-year survival was reduced to 38.3% (P-value: <0.001). The poorest 5-year survival (23.8%; P-value: <0.001) was observed in Cluster 4 with biatrial dilatation (left atrial volume: 312 ± 113 mL; right atrial area: 46.0 ± 8.83 cm2) although LVEF was only slightly reduced (51.5 ± 11.0%). Importantly, the prognostic significance of ML-derived phenotypes was externally confirmed.

Conclusion

ML-enabled phenotyping captures the complexity of extra-mitral valve cardiac damage, which does not necessarily occur in a sequential fashion. This novel phenotyping approach can refine risk stratification in patients undergoing MV TEER in the future.
Premature atrial and ventricular contractions detected on wearable-format electrocardiograms and prediction of cardiovascular events
Authors: Orini Michele , van Duijvenboden Stefan , Young William J , Ramírez Julia , Jones Aled R , Tinker Andrew , Munroe Patricia B , Lambiase Pier D
Published: February 2023

Aims

Wearable devices are transforming the electrocardiogram (ECG) into a ubiquitous medical test. This study assesses the association between premature ventricular and atrial contractions (PVCs and PACs) detected on wearable-format ECGs (15 s single lead) and cardiovascular outcomes in individuals without cardiovascular disease (CVD).

Methods and results

Premature atrial contractions and PVCs were identified in 15 s single-lead ECGs from N = 54 016 UK Biobank participants (median age, interquartile range, age 58, 50–63 years, 54% female). Cox regression models adjusted for traditional risk factors were used to determine associations with atrial fibrillation (AF), heart failure (HF), myocardial infarction (MI), stroke, life-threatening ventricular arrhythmias (LTVAs), and mortality over a period of 11.5 (11.4–11.7) years. The strongest associations were found between PVCs (prevalence 2.2%) and HF (hazard ratio, HR, 95% confidence interval = 2.09, 1.58–2.78) and between PACs (prevalence 1.9%) and AF (HR = 2.52, 2.11–3.01), with shorter prematurity further increasing risk. Premature ventricular contractions and PACs were also associated with LTVA (P < 0.05). Associations with MI, stroke, and mortality were significant only in unadjusted models. In a separate UK Biobank sub-study sample [UKB-2, N = 29,324, age 64, 58–60 years, 54% female, follow-up 3.5 (2.6–4.8) years] used for independent validation, after adjusting for risk factors, PACs were associated with AF (HR = 1.80, 1.12–2.89) and PVCs with HF (HR = 2.32, 1.28–4.22).

Conclusion

In middle-aged individuals without CVD, premature contractions identified in 15 s single-lead ECGs are strongly associated with an increased risk of AF and HF. These data warrant further investigation to assess the role of wearable ECGs for early cardiovascular risk stratification.
Real-world clinical outcomes with a next-generation left atrial appendage closure device: the FLXibility Post-Approval Study
Authors: Betts Tim R , Grygier Marek , Nielsen Kudsk Jens Erik , Schmitz Thomas , Sandri Marcus , Casu Gavino , Bergmann Martin , Hildick-Smith David , Christen Thomas , Allocco Dominic J ,   For the FLXibility investigators
Published: February 2023

Aims

The FLXibility Post-Approval Study collected data on unselected patients implanted with a WATCHMAN FLX in a commercial clinical setting.

Methods and results

Patients were implanted with a WATCHMAN FLX per local standard of care, with a subsequent first follow-up visit from 45 to 120 days post-implant and a final follow-up at 1-year post-procedure. A Clinical Event Committee adjudicated all major adverse events and TEE/CT imaging results were adjudicated by a core laboratory. Among 300 patients enrolled at 17 centres in Europe, the mean age was 74.6 ± 8.0 years, mean CHA2DS2-VASc score was 4.3 ± 1.6, and 62.1% were male. The device was successfully implanted in 99.0% (297/300) of patients. The post-implant medication regimen was DAPT for 87.3% (262/300). At first follow-up, core-lab adjudicated complete seal was 88.2% (149/169), 9.5% (16/169) had leak <3 mm, 2.4 (4/169) had leak ≥3 mm to ≤5 mm, and 0% had >5 mm leak. At 1 year, 93.3% (280/300) had final follow-up; 60.5% of patients were on a single antiplatelet medication, 21.4% were on DAPT, 5.6% were on direct oral anticoagulation, and 12.1% were not taking any antiplatelet/anticoagulation medication. Adverse event rates through 1 year were: all-cause death 10.8% (32/295); CV/unexplained death 5.1% (15/295); disabling and non-disabling stroke each 1.0% (3/295, all non-fatal); pericardial effusion requiring surgery or pericardiocentesis 1.0% (3/295); and device-related thrombus 2.4% (7/295).

Conclusion

The WATCHMAN FLX device had excellent procedural success rates, high LAA seal rates, and low rates of thromboembolic events in everyday clinical practice.
Performance Based on Measurements from Individual-Tree Progeny Tests Strongly Predicts Early Stand Yield in Loblolly Pine
Authors: Shalizi Mohammad Nasir , Walker Trevor D , Heine Austin J , Payn Kitt G , Isik Fikret , Bullock Bronson P , McKeand Steven E
Published: February 2023

To facilitate the utility of genetic improvement in loblolly pine, individual-tree volume (productivity) scores estimated from single-tree plot or row-plot progeny test designs were compared with stand-level volume per unit area from block plots. A large number of families representing a wide range of progeny test scores for volume were established in growth and yield trials to generalize the results to families created by the breeding program. Individual-tree volume scores from progeny tests strongly corresponded with stand-level volume from block plots, especially after accounting for site quality and the risk of fusiform rust disease. A ten-point increase in the volume score from progeny test data was estimated to increase stand-level volume by 3.9 m3 ha-1 at age 6 years. A prediction model is presented that includes a new statistic, rust risk index, which is the expected rust incidence for a family at a new site when the hazard of rust for a checklot can be estimated from historical data. The study results through age 6 years corroborate the Performance Rating System as effective in guiding family deployment decisions. The models presented are based on pre-crown closure data at 6 years and will be updated with older measurements as the study matures.

Study Implications: The Performance Rating System (PRS™) has been a successful tool for presenting genetic merit of improved loblolly pine families for landowners and forest managers in a more coherent and standardized manner. This system can be easily applied in other forest tree improvement programs, because it makes genetic improvement user-friendly for silviculturists and forest managers. Landowners can use this system to make decisions for selecting improved families suited to their specific forest management objectives. Seed orchard and nursery managers also depend on the PRS to choose the families to produce and as a third-party verification to market their genetic merit to customers. This study demonstrates that higher stand-level volume per unit area can be achieved when forest managers plant fast growing families with low fusiform rust disease risk on productive sites. The combined effect of genetic improvement for productivity and fusiform rust disease resistance is significant on stand-level volume per unit area.