bluuebunny/crossref_metadata_2025 huggingface dataset:
Parametric simulator of cyclic and non-cyclic impulsive vibration signals for diagnostic research applications
Authors: Michalak Anna , Wodecki Jacek
Published: December 2021

In recent years cyclostationary analysis of vibration signals is considered to be one of the most potent approaches for diagnostics of machines with rotating components. However, it is a subject of an extensive research towards extending its robustness due to its significant inefficiency in the presence of non-cyclic impulsive components in measured data. This problem is especially visible in datasets measured on machines such as ore crushers, where the high-energy impacts are a natural phenomenon. Unfortunately, due to practical inaccessibility, real-life datasets necessary to properly study this problem are extremely difficult to obtain. To address this issue, the authors propose an easy to use simulator of impulsive components. It covers both cyclic components that can describe various types of fault signatures, and non-cyclic ones that can represent impacts occurring naturally due to the nature of machine operation. Simulated signals have been compared with real ones to ensure a high similarity degree, which in turn guarantees a relatively high level of realism.
Analysis of the vibro-acoustic data from test rig -comparison of acoustic and vibrational methods
Authors: Zimroz Paweł , Shiri Hamid , Wodecki Jacek
Published: December 2021

Detection of damage is a significant issue in providing efficiency and safety in industrial processes. In underground mining much research effort is made for developing an automatic system of diagnosing the machinery using robots. One of the major groups of equipment utilized and maintained in the mines is rotating machinery. Local damage occurring in such machines commonly have a cyclostationary character in short term as any change in their characteristics is expected to repeat periodically. In most cases they can be easily detected based on vibration signals measured with contact sensors (accelerometers). However if mobile robots such as UAV (unmanned aerial vehicles) are planned to be used, remote measurement is firmly preferred. In this paper we compare vibrational detection with a novel approach based on analysing an acoustic signal recorded by a microphone.
Preliminary sources identification of nitric oxide (NO) emissions in underground mine
Authors: Banasiewicz Aleksandra , Wroblewski Adam , Gola Sebastian
Published: December 2021

Gas hazards in Polish underground mines are a major problem for the ventilation service. Ensuring appropriate environmental conditions is becoming increasingly difficult, especially with the introduction of new, more stringent restrictions on the concentration limits of harmful gases. According to [1], the most dangerous gases in underground mines are carbon monoxide, hydrogen sulfide, nitrogen oxides, c arbon dioxide, sulfur dioxide, and m e thane. T ogether with the introduction of new limit values for the above-mentioned gases by the European Union, it is necessary to accurately identify the sources of their emission in mine workings in order to select an appropriate reduction method. This article presents daily measurements of nitric oxide (NO) concentrations in the workings of one of the copper ore mines owned by KGHM Polska Miedź S.A. The measurement results were used for preliminary analysis of sources of gas emissions to underground workings. The analysis is carried out through a graphical interpretation of the measured values. Knowing the details of the technological processes carried out in the mine under consideration (blasting, diesel engine machines, natural oxidation of nitrogen to NO) the graphs were interpreted by assigning individual values of NO concentrations over time to a specific t echnological process.
Self-healing of asphalt mixture: the impact of the minerals forming the aggregates in the efficiency of the heating by microwaves.
Authors: Trigos L , Gallego J , Escavy JI , Ayala D
Published: December 2021

The current concern for the environment and the need to reduce greenhouse gas emissions have led to new technologies related to microwave energy. One of these technologies is the self-healing of asphalt mixtures, which consists of repairing pavements through microwave application on the surface, avoiding premature road failure. Asphalt mixtures for roads are made up of more than 90% by weight of aggregates of different compositions and origins, in addition to a bituminous binder and sometimes additives. From other studies, it is known that the physical behaviour of aggregates is a function of their composition, that is, of their minerals and their proportions. Microwave heating of aggregates has proven to be an effective technique, but there are gaps in understanding how microwaves interact with aggregates and the reasons for their differential heating.

This research has studied 18 minerals that are commonly part of the rocks used as road aggregates. The objective is to identify the minerals that present the best heating rates to relate them to the differential heating of aggregates for roads. The results obtained are promising, facilitating the understanding of microwave heating of minerals. Regarding chemical composition, elements such as MgO, MnO, TiO, Al2O3, Fe2O3, and CaO (in silicate minerals) favour the heating of minerals and other elements such as SiO2 and K2O Na2O, and CaO (in carbonate minerals) retard the heating. Regarding the physical properties, density and habit of the minerals do not influence the heating, but other properties, such as the diaphaneity and the size of the crystals, influence the heating with microwaves.
Strength properties of ballast layer, created from new and recycled crushed stone ballast
Authors: Leus Oleksii , Menendez Pidal Ignacio , Kolos Aleksey , Klishch Sergei
Published: December 2021

The objective of the research is a railway ballast layer created from new and recycled ballast particles in different ratio. In order to study the possibility of using recycled ballast grains in ballast layer, it is necessary to carry out laboratory triaxial tests of ballast crushed stone with size of the particles 25-60 mm with different grain shape. Abrasion testing machine allows to reach the effect on new ballast, which is similar to abrasion of ballast particles in the railway track. Therefore, it is possible to create ballast samples from (new) mixed and recycled ballast and estimate which proportion has the strength characteristics, which are close to the ones in ballast layer created only with new ballast particles. The result of the study shows, that it makes sense to return the recycled crushed stone in a mix with a new one in order to reduce the cost on a railway maintenance.
Hilbert transform using a robust geostatistical method
Authors: Marashly O , Dobroka M
Published: December 2021

In this paper, we introduced an efficient inversion method for Hilbert transform calculation which can be able to eliminate the outlier noise. The Most Frequent Value method (MFV) developed by Steiner merged with an inversion-based Fourier transform to introduce a powerful Fourier transform. The Fourier transform process (IRLS-FT) ability to noise overthrow efficiency and refusal to outliers make it an applicable method in the field of seismic data processing. In the first part of the study, we introduced the Hilbert transform stand on a efficient inversion, after that as an example we obtain the absolute value of the analytical signal which can be used as an attribute gauge. The method depends on a dual inversion, first we obtain the Fourier spectrum of the time signal via inversion, after that, the spectrum calculated via transformation of Hilbert transforms into time range using a efficient inversion. Steiner Weights is used later and calculated using the Iterative Reweighting Least Squares (IRLS) method (efficient inverse Fourier transform). Hermite functions in a series expansion are used to discretize the spectrum of the signal in time. These expansion coefficients are the unknowns in this case. The test procedure was made on a Ricker wavelet signal loaded with Cauchy distribution noise to test the new Hilbert transform. The method shows very good resistance to outlier noises better than the conventional (DFT) method.
Image segmentation methods for quick characterization of ore chip using RGB images
Authors: Khomiak O , Benndorf J
Published: December 2021

The ability to forecast geometallurgical properties during resource extraction is essential to optimize the mine to mill process. Models for mine planning thus often incorporate attributes related to processability. The analysis of these attributes in a laboratory can be time- and cost intensive. Only a limited number of data may be available. During production, grade control drilling may provide access to many more samples. Conducting laboratory analysis to each of these samples would be not realistic. If there was an opportunity to quickly obtain related proxy data, as physical characteristics that can stand in for direct measurements, then these indices could be estimated, certainly less precise but with a significantly increased spatial density. A moderately simple approach to acquire data from grade control drilling is to take digital Red, Green and Blue spectral bands images (RGB images) in from core trays. Although these capture only three spectral band regions, images can contain valuable texture and colour related information. A first necessary step is to automatically extract from an image and analyse objects, that represent ore particles or mineral content. This study aims to investigate the performance of different available segmentation methods under field conditions. First an overview of methods for image segmentation as a basis to create objects is presented. Objects can be related to single grains and minerals within the grains. The aim is to provide a basis for texture feature extraction related to granular rock, such as found in chip trains. Modern image analysis provides a large number of methods for segmentation and classification of objects. This work focuses on evaluating performance on images of 3 levels of complexity of pixel- based segmentation for complex or less noisy images and object-based segmentation (Watershed, Simple Linear Iterative Clustering and Quickshift) as a more advanced and universal method.
Qualitative assessment of the complexity of the Karman vortex in the flow past double cylinders based on Shannon entropy
Authors: Jia Tao , Zhang Sen , Gao Di
Published: December 2021

Numerical simulations of flows past double cylinders under the conditions of different inlet velocities are carried out based on finite element methods. The phenomenon of Karman vortex is observed in the numerical study. Shannon entropy of the velocity field is calculated to quantify the complexity of the velocity field, and the time-evolution of the Shannon entropy data is analyzed by time series models of autoregressive moving average and generalized autoregressive conditional heteroskedasticity.
Free-space to single-mode fiber coupling efficiency with optical system aberration and fiber positioning error under atmospheric turbulence
Authors: Bian Yiming , Li Yan , Chen Erhu , Li Wei , Hong Xiaobin , Qiu Jifang , Wu Jian
Published: December 2021

Benefiting from the rapid development of fiber-optic devices, high-speed free-space optical (FSO) communication systems have recently used fiber-optic components. The received laser beam in such a system couples into single-mode fiber (SMF) at the input of the receiver module. This work is oriented to common problems in actual FSO coupling systems, such as atmospheric turbulence, optical system aberration (OSA), and fiber positioning error. We derive the statistical expectation models of SMF coupling efficiency with OSA in the presence of atmospheric turbulence and the statistical expectation models of SMF coupling efficiency with fiber positioning error in the presence of atmospheric turbulence. The influences of OSA and fiber positioning error on the coupling efficiency under different turbulence strengths are also analyzed in this paper.
The evaluation of microstructure, grain boundary character and micro texture of [Al/Si3N4/Al2O3] P nanocomposites fabricated through PM route and its influence on compressive and three-body wear properties
Authors: Kothiyal Pradeep , Joshi Amit , Mer K K S , Verma Raviraj
Published: December 2021

The compressive properties and 3 body wear characteristics of powder metallurgical (PM) processed [Al/Si3N4/Al2O3] P Nanocomposites with single and combined reinforcement of Al2O3 and Si3N4 reinforcing particles having different compositions (1%, 2% and 3%) were studied and evolution of microstructure, grain boundary character and micro texture of fabricated [Al/Si3N4/Al2O3] P Nanocomposites was investigated through EBSD in the present research work. The fraction of high angle boundaries (HAGBs) were observed more in combined reinforcing samples of Al2O3 and Si3N4 whereas a single reinforcing sample of Al2O3 and Si3N4 showed fewer HAGBs. Micro texture results showed the strong textures components near to {112}〈111 〉 Cu and {110}〈111 for pure sintered Al sample P and mixed reinforcement composites (M1, M2 and M3) > P whereas for single reinforcing sample showed weak textures near to transverse direction. Out of all fabricated composites, 2% mixed Al2O3 and Si3N4 reinforced composite revealed the maximum ultimate compressive strength (209.98 MPa) and least wear rate (0.1 mm3/min mm3/N-cm for 1 kg load and 3.5 mm3/N-cm for 2 kg load) attributing formation of nanocluster causing grain boundary pinning effect. The dominant failure mechanism for all samples was also detected and found to be a mixed-mode ductile failure mechanism for 2% mixed Al2O3 and Si3N4 reinforcement composite while other sample failed through ductile as well as mixed-mode mechanisms.
Effect of carbon source on the properties of dense α-SiC
Authors: Aygüzer Yaşar Zeynep , DeLucca Vincent A , Haber Richard A
Published: December 2021

Due to its outstanding properties, SiC is a candidate material for use in special applications such as armor. In order to use SiC in these special applications, it is necessary to produce fully dense ceramics. The ability to produce high density materials with superior performance depends on a number of factors. One of these factors is the addition of carbon to aid sintering. In this study, the effect of different carbon sources and ratios on the elastic and mechanical properties of SiC was investigated. Two types of carbon (lamp black and phenolic resin) were added to SiC in different ratios (0%–2% wt.). All samples were sintered via the spark plasma sintering (SPS) method at 1900 °C for 15 min under 50 MPa pressure. Samples made with lamp black were reached full density at 1.0 wt.%C, and the hardness and elastic modulus values were ∼22GPa and 440 GPa, respectively. While samples made with both carbon sources showed similar bulk mechanical properties, the samples made with lamp black showed more consistent microstructures. The carbon from the phonelic resin source did not appear to be as well distributed as that from the lamp black source. The results also confirmed that addition of carbon into SiC was essential to improve the density and other mechanical properties associated with it.
Thermal-cycling, simulated brushing, and beverages induced color changes and roughness of CAD/CAM poly (methyl methacrylate) denture resins
Authors: Al Taweel Sara Mohammad , Fouzan Afnan Al , Al-Otaibi Hanan N , Labban Nawaf , AlShehri Huda A
Published: December 2021

The aim of the present study was to evaluate and compare the effect of thermal-cycling, mechanical brushing and beverage storage on the colour changes and surface roughness of conventional heat-polymerized and CAD/CAM PMMA used to fabricate complete dentures. A total of 100 specimens measuring 10 mm in diameter and 3 mm in thickness were fabricated from conventional PMMA resin (Heat-cured, Major. Base.20, Moncalieri, Italy) and CAD/CAM blocks (Opera system, Principauté de Monaco, French). The specimens were subjected to a combined surface treatment involving thermo-cycling, mechanical brushing, and immersed in either artificial saliva (AS), coffee, tea, Coca-Cola, or lemon juice. Colour differences (ΔE) and surface roughness (Ra) was determined using a spectrophotometer and non-contact profilometer, respectively. The data were analyzed using IBM SPSS v.20 (α = 0.05). Factorial ANOVA showed that independent factors, namely material, beverages, and the interaction between independent factors, significantly influenced ΔE (F = 76.862; p < 0.001) and surface roughness (F = 71.685; p < 0.001). The overall highest and lowest colour differences was obtained for CAD/CAM PMMA (ΔE = 1.93 ± 1.29) and conventional PMMA (ΔE = 1.41 ± 1.39) resins, respectively (p = 0.061). Conventional PMMA (1.22 ± 0.20) demonstrated significantly increased roughness compared to CAD/CAM PMMA (0.91 ± 0.17) (p < 0.001). Pearson correlation showed a low degree of correlation, which was non-significant for both the PMMA (r = 0.015; p = 0.917) and C-PMMA materials (r = 0.097; p = 0.505). CAD/CAM milled PMMA resins demonstrated greater colour change and lower surface roughness compared to conventional heat-polymerized PMMA resins. Specimens in tea and coffee demonstrated maximum colour changes and were perceivable by the human eye. On the contrary, specimens immersed in low pH acidic beverages namely Coca-Cola and lemon juice demonstrated maximum surface roughness.
Compressive mechanical behavior and model of composite elastic-porous metal materials
Authors: Yang Pei , Zhou Tao , Jia Di , Qin Zhiqiang , Wu Yiwan , Bai Hongbai
Published: December 2021

This work presents the experimental characterization and theoretical modeling of composite elastic-porous metal materials (C-EPMM). C-EPMM is a novel porous metallic damping material made of wire mesh and wire helix. A series of quasi-static compressive experiments were carried out to investigate the stiffness and energy absorption ability of the C-EPMM with different mass ratios. The experimental results show that the mass ratios can significantly affect the stiffness and loss factor of C-EPMM. To efficiently predict the nonlinear mechanical properties of the C-EPMM a theoretical model of C-EPMM was proposed for the first time, the model was based on the manufacturing process. A comparison between the predicted data and the experimental data was conducted. The results show that the theoretical model can accurately predict the mechanical performance of C-EPMM. The conclusions derived from this work can provide a new method for adjusting the mechanical performance of EPMM in applications.
A Monte Carlo study of different LET definitions and calculation parameters for proton beam therapy
Authors: Smith Edward A K , Winterhalter Carla , Underwood Tracy S A , Aitkenhead Adam H , Richardson Jenny C , Merchant Michael J , Kirkby Norman F , Kirby Karen J , Mackay Ranald I
Published: December 2021

The strong in vitro evidence that proton Relative Biological Effectiveness (RBE) varies with Linear Energy Transfer (LET) has led to an interest in applying LET within treatment planning. However, there is a lack of consensus on LET definition, Monte Carlo (MC) parameters or clinical methodology. This work aims to investigate how common variations of LET definition may affect potential clinical applications. MC simulations (GATE/GEANT4) were used to calculate absorbed dose and different types of LET for a simple Spread Out Bragg Peak (SOBP) and for four clinical PBT plans covering a range of tumour sites. Variations in the following LET calculation methods were considered: (i) averaging (dose-averaged LET (LETd) & track-averaged LET); (ii) scoring (LETd to water, to medium and to mass density); (iii) particle inclusion (LETd to all protons, to primary protons and to particles); (iv) MC settings (hit type and Maximum Step Size (MSS)). LET distributions were compared using: qualitative comparison, LET Volume Histograms (LVHs), single value criteria (maximum and mean values) and optimised LET-weighted dose models. Substantial differences were found between LET values in averaging, scoring and particle type. These differences depended on the methodology, but for one patient a difference of ∼100% was observed between the maximum LETd for all particles and maximum LETd for all protons within the brainstem in the high isodose region (4 keV μm−1 and 8 keV μm−1 respectively). An RBE model using LETd including heavier ions was found to predict substantially different LET-weighted dose compared to those using other LET definitions. In conclusion, the selection of LET definition may affect the results of clinical metrics considered in treatment planning and the results of an RBE model. The authors’ advocate for the scoring of dose-averaged LET to water for primary and secondary protons using a random hit type and automated MSS.
Degree of reduction in normal liver complication probability from free-breathing to breath-hold liver SBRT: a dose-escalation strategy using radiation dose-volume effect
Authors: Thaper Deepak , Yadav Hanuman P , Sharma Deepti , Kamal Rose , Singh Gaganpreet , Oinam Arun S. , Kumar Vivek
Published: December 2021

Introduction. This study aimed to analyze the degree of reduction in normal liver complication probability (NTCP) from free-breathing (FB) to breath-hold (BH) liver SBRT. The effect of the radiation dose-volume on the mean liver dose (MLD) was also analyzed due to dose prescription, normal liver volume (NLV), and PTV. Materials and Methods. Thirty-three stereotactic body radiation therapy (SBRT) cases of hepatocellular carcinoma were selected, retrospectively. For FB, the treatments were planned on average intensity projection scan (CTavg), and patient-specific internal target volume (ITV) margins were applied. To simulate the BH treatment, computed tomography (CT) scan correspond to the 40%—50% of the respiratory cycle (CT40%-50%) was chosen, and an appropriate intrafraction margin of 2 mm, 1.5 mm, and 1.5 mm were given in craniocaudal (CC), superior-inferior (SI), and lateral direction to generate the final iGTV. As per RTOG 1112, all organs at risk (OAR’s) were considered during the optimization of treatment plans. NTCP was calculated using LKB fractionated model. Multivariate regression analysis was performed to see the effect of EQD2Gy, NLV, and PTV on MLD2Gy. Results. A significant dosimetric difference was observed in the normal liver (liver-ITV/iGTV). A reduction of 1.7% in NTCP was observed from FB to BH technique. The leverage of dose escalation is more in BH because MLD2Gy corresponds to 5%, 10%, 20%, and 50% NTCP was 0.099 Gy, 0.41 Gy, 1.21 Gy, and 3.432 Gy more in BH as compared to FB technique. In MVRA, the major factor which was attributed to a change in MLD2Gy is EQD2Gy. Conclusion. From FB to BH technique, a significant reduction in NTCP was observed. The dose prescription is a major factor attributed to the change in MLD2Gy. Advances in knowledge: If feasible, prefer BH treatment either for tumor dose escalation or for the reduction in NTCP.
General overestimation of ERA5 precipitation in flow simulations for High Mountain Asia basins
Authors: Sun He , Su Fengge , Yao Tandong , He Zhihua , Tang Guoqiang , Huang Jingheng , Zheng Bowen , Meng Fanchong , Ou Tinghai , Chen Deliang
Published: December 2021

Precipitation is one of the most important input to hydrological models, although obtaining sufficient precipitation observations and accurate precipitation estimates in High Mountain Asia (HMA) is challenging. ERA5 precipitation is the latest generation of reanalysis dataset that is attracting huge attention from various fields but it has not been evaluated in hydrological simulations in HMA. To remedy this gap, we first statistically evaluated ERA5 precipitation with observations from 584 gauges in HMA, and then investigated its potential in hydrological simulation in 11 HMA basins using the Variable Infiltration Capacity (VIC) hydrological model. The ERA5 precipitation generally captures the seasonal variations of gauge observations, and the broad spatial distributions of precipitation in both magnitude and trends in HMA. The ERA5 exhibits a reasonable flow simulation (RB of 5%–10%) at the Besham hydrological station of the upper Indus (UI) basin when the contribution from glacier runoff is added to the simulated total runoff. But it overestimates the observations in other HMA basins by 33%–106% without considering glacier runoff, mostly due to the overestimates in the ERA5 precipitation inputs. Therefore, a bias correction is definitely needed before ERA5 precipitation is used for hydrological simulations in HMA basins.
Nitrogen use efficiency trends for sustainable crop productivity in Lake Victoria basin: smallholder farmers’ perspectives on nitrogen cycling
Authors: Ntinyari Winnie , Gweyi-Onyango Joseph , Giweta Mekonnen , Mochoge Benson , Mutegi James , Nziguheba Generose , Masso Cargele
Published: December 2021

Nitrogen Use Efficiency (NUE) is one of the established metrics for benchmarking management of Nitrogen (N) in various systems. Numerous approaches to calculate NUE exist, making it difficult to compare the performances of systems depending on the methodology used. This study adopted the conceptualized framework by European Union Nitrogen Expert Panel (EUNEP) to calculate NUE values for cereal crops to determine future trends for the first time in the Lake Victoria region. Data were collected through in-person interviews among maize and rice smallholder farmers within the Lake Victoria region. A total of 293 observations were recorded. Collected data on yield and N fertilizer were used to make projections on the changes of NUE based on scientific and policy recommendations for Sub-Saharan Africa for 2020 (base year), 2025, 2030, and 2050. Significant differences in maize grain yield for both fertilized and unfertilized farms were observed with very low yields of 2.4 t ha−1 (fertilized) and 1.4 t ha−1 (unfertilized). The graphical representation of NUE of both maize and rice showed that most farmers were in the zone of soil N mining. Projected results showed that most maize farmers within Lake Victoria region will continue to experience NUE values >90%, low N inputs <50 kg N ha−1) and less than 5 t ha−1 maize crop yield over the years. For rice farmers, Nyando and Nzoia catchments had surpassed the set target of both yield (6 t ha−1) and N input (50 kg N ha−1). However, NUE values remain higher than the optimal ranges of 50%–90% (127.14%−267.57%), indicating risks of depleting soil N status. The unbalanced N fertilization also showed a trend below the linear neutrality option and the average N output for good N management for both crops. Therefore, farmers need to explore various crop management options that could increase N use efficiencies. This should be coupled with policies that promote farmers to access more N input and advocate for optimal management of N and improved quality of the cereals.
Experimental study of thermal limits with one-side heated smooth channel for plasma facing component safety
Authors: Lim Ji Hwan , Park Minkyu
Published: December 2021

In order to stably operate the equipment inside the tokamak, which is loaded with a heat flux of several MW m−2 under the one-side heating condition, it is necessary to thoroughly prepare for various thermal engineering limits that may occur under the high heat flux load condition. In this study, we have experimentally explored critical heat flux (CHF) and onset of flow instability (OFI), which are considered potential threats in a DEMO fusion power plant. Specifically, the effect of system parameters on CHF was investigated. The results indicate that with an increase in subcooling and mass flux, the CHF increased, as it induced a faster bubble condensation near the CHF. As the system pressure increased, the CHF also increased. This is because the bubble size reduction effect was dominant in the pressure range of 1–10 bar. Most of the existing CHF correlations could evaluate the CHF with reasonable accuracy of within 25%; especially, the Boscary CHF correlation yielded the highest accuracy with an average error of 12%. Similar to CHF, OFI, which is a measure of the sudden fluctuations in the system pressure caused by a large amount of vapor generated due to the high heat flux, tended to increase as the subcooling, mass flow rate, and system pressure increased. Most of the existing OFI correlations yielded large error rates (more than 135%) as these correlations were primarily developed for micro-channels. Therefore, in this study, a new OFI correlation was developed using a Python code, in combination with an artificial intelligence (AI) regression method. The developed correlation can be used in the cooling system design of tokamaks, which involve a high-heat load condition on one-side of the reactor.
Air delay propagation patterns in Europe from 2015 to 2018: an information processing perspective
Authors: Pastorino Luisina , Zanin Massimiliano
Published: December 2021

The characterisation of delay propagation is one of the major topics of research in air transport management, due to its negative effects on the cost-efficiency, safety and environmental impact of this transportation mode. While most research works have naturally framed it as a transportation process, the successful application of network theory in neuroscience suggests a complementary approach, based on describing delay propagation as a form of information processing. This allows reconstructing propagation patterns from the dynamics of the individual elements, i.e. from the evolution observed at individual airports, without the need of additional a priori information. We here apply this framework to the analysis of delay propagation in the European airspace between 2015 and 2018, describe the evolution of the observed structure, and identify the role of individual airports in it. We further use this analysis to illustrate the limitations and challenges associated to this approach, and to sketch a roadmap of future research in this evolving topic.
Chemformer: a pre-trained transformer for computational chemistry
Authors: Irwin Ross , Dimitriadis Spyridon , He Jiazhen , Bjerrum Esben Jannik
Published: December 2021

Transformer models coupled with a simplified molecular line entry system (SMILES) have recently proven to be a powerful combination for solving challenges in cheminformatics. These models, however, are often developed specifically for a single application and can be very resource-intensive to train. In this work we present the Chemformer model—a Transformer-based model which can be quickly applied to both sequence-to-sequence and discriminative cheminformatics tasks. Additionally, we show that self-supervised pre-training can improve performance and significantly speed up convergence on downstream tasks. On direct synthesis and retrosynthesis prediction benchmark datasets we publish state-of-the-art results for top-1 accuracy. We also improve on existing approaches for a molecular optimisation task and show that Chemformer can optimise on multiple discriminative tasks simultaneously. Models, datasets and code will be made available after publication.
Algebraic approximations of fibrations in abelian varieties over a curve
Authors: Lin Hsueh-Yung
Published: December 2021

For every fibration

f
:
X
→
B

f : X \to B

with

X
X

a compact Kähler manifold,

B
B

a smooth projective curve, and a general fiber of

f
f

an abelian variety, we prove that

f
f

has an algebraic approximation.
Reputational versus Beckerian Sanctions
Authors: Fluet Claude , Mungan Murat C
Published: December 2021

Legal sanctions cause reputational losses in addition to the direct losses. Lowering the probability of punishment reduces these reputational losses by diluting the informational value of verdicts. These considerations better align the positive as well as normative implications of law enforcement models with intuition and empirics: violations of the law are more responsive to the certainty rather than the severity of punishment even absent risk-seeking offenders (positive), which causes extreme Beckerian punishments to be inefficient when sanctions are socially costly to impose (normative). Moreover, in some cases optimal enforcement is “anti-Beckerian”: punishment is symbolic, and detection costs are incurred solely to provide reputational incentives.
Cohort consequences of drought and family disruption for male and female African elephants
Authors: Lee Phyllis C , Moss Cynthia J , Njiraini Norah , Poole Joyce H , Sayialel Katito , Fishlock Vicki L
Published: December 2021

Cohort effects, reflecting early adversity or advantage, have persisting consequences for growth, reproductive onset, longevity, and lifetime reproductive success. In species with prolonged life histories, cohort effects may establish variation in age-sex structures, while social structure may buffer individuals against early adversity. Using periods of significant ecological adversity, we examined cohort effects for male and female elephants (Loxodonta africana) over almost 50 years in Amboseli, Kenya. Mortality spiked during severe droughts with highest mortality among calves under 2 years and females over 40 years. Deaths of oldest females resulted in social disruption via matriarch turnover, with potential impacts on resource acquisition for survivors. We predicted that survivors of high mortality and social challenges would have altered life-history trajectories, with later age at first reproduction and reduced age-specific fertility for females and slow transitions to independence and late-onset of potential mating or musth among males. Contrary to expectations, there were no persisting early drought effects on female age at first conception while matriarch loss around puberty accelerated reproductive onset. Experience of an early life drought did not influence age-specific reproductive rates once females commenced reproduction. Males who survived an early drought exhibited complex consequences: male age at family independence was later with larger peer cohort size, but earlier with drought in year of independence (13.9 vs 14.6 years). Early drought had no effect on age at first musth, but male reproductive onset was weakly associated with the number of peers (negative) and age at independence (positive).
Immunotherapy for type 1 diabetes
Authors: Allen L A , Dayan C M
Published: December 2021

Introduction

Despite advances in technology including the development of more sophisticated methods of monitoring blood glucose and delivering insulin, many individuals with type 1 diabetes continue to experience significant challenges in optimizing glycaemic control. Alternative treatment approaches to insulin are required. Increasing efforts have focused on developing treatments aimed at targeting the underlying disease process to modulate the immune system, maximize beta cell function and enhance endogenous insulin production and action.

Sources of data

Literature searches with keywords ‘Type 1 diabetes and immunotherapy’, publications relating to clinical trials of immunotherapy in type 1 diabetes.

Areas of agreement

Insulin therapy is insufficient to achieve optimal glycaemic control in many individuals with type 1 diabetes, and new treatment approaches are required. Studies have showed promising results for the use of immunotherapy as a means of delaying disease onset and progression.

Areas of controversy

The optimal way of identifying individuals most likely to benefit from immunotherapies.

Growing points

A better understanding of the natural history of type 1 diabetes has made it possible to identify individuals who have developed autoimmunity but have not yet progressed to clinical diabetes, offering opportunities not only to develop treatments that delay disease progression, but prevent its development in the first place. A consensus on how to identify individuals who may benefit from immunotherapy to prevent disease onset is needed.

Areas timely for developing research

The development of optimal strategies for preventing and delaying progression of type 1 diabetes, and monitoring the response to immunointervention.
Global connectivity fingerprints predict the domain generality of multiple-demand regions
Authors: Schultz Douglas H , Ito Takuya , Cole Michael W
Published: December 2021

A set of distributed cognitive control networks are known to contribute to diverse cognitive demands, yet it is unclear how these networks gain this domain-general capacity. We hypothesized that this capacity is largely due to the particular organization of the human brain’s intrinsic network architecture. Specifically, we tested the possibility that each brain region’s domain generality is reflected in its level of global (hub-like) intrinsic connectivity as well as its particular global connectivity pattern (“connectivity fingerprint”). Consistent with prior work, we found that cognitive control networks exhibited domain generality as they represented diverse task context information covering sensory, motor response, and logic rule domains. Supporting our hypothesis, we found that the level of global intrinsic connectivity (estimated with resting-state functional magnetic resonance imaging [fMRI]) was correlated with domain generality during tasks. Further, using a novel information fingerprint mapping approach, we found that each cognitive control region's unique rule response profile(“information fingerprint”) could be predicted based on its unique intrinsic connectivity fingerprint and the information content in regions outside cognitive control networks. Together, these results suggest that the human brain’s intrinsic network architecture supports its ability to represent diverse cognitive task information largely via the location of multiple-demand regions within the brain’s global network organization.
Riata lead failure manifests as electrical storm with lead parameters showing unique postural variations: a case report
Authors: Uppal Abhimanyu , Kathuria Sanjeev , Shah Bhushan , Trehan Vijay
Published: December 2021

Background

Riata implantable cardioverter-defibrillator (ICD) leads are prone to a unique type of mechanical lead failure causing conductor externalization (CE) which may be complicated by a delayed-onset electrical lead failure (ELF).

Case summary

A 60-year-old male with symptomatic, severe ischaemic cardiomyopathy, and atrial fibrillation following a prior anterior wall myocardial infarction received a dual-chamber ICD with 7F-RiataST ventricular lead as a primary prevention strategy against sudden cardiac death in 2008. In 2017, a pulse generator replacement was performed for elective replacement indicator status. At that time, CE was noted in the ventricular lead but the electrical lead parameters were normal, hence lead replacement was decided against and the patient was closely followed up thereafter. Four years later, the patient presented with multiple ICD shocks within 48 h. Implantable cardioverter-defibrillator interrogation showed noise on the ventricular electrogram (EGM) channel that was detected as ventricular fibrillation (VF) episodes, triggering inappropriate ICD therapy (five ICD detected VF events within 24 h triggering three antitachycardia pacing therapies and one shock). Lead impedance and R-wave amplitude were within normal range in supine position but dramatically worsened in sitting posture. A new ventricular lead was implanted and the old lead abandoned. The patient has not experienced any device therapy in the follow-up period.

Discussion

An electrically inert CE of Riata ICD leads needs close follow-up because an ELF may occur even after several years. A careful analysis of EGMs including postural changes in lead parameters can aid in detection and better characterization of underlying electrical dysfunction following CE.
Mechanical circulatory support and intravascular lithotripsy in high-risk patients undergoing percutaneous coronary intervention and transcatheter aortic valve replacement: a case series
Authors: Marchese Alfredo , Tarantini Giuseppe , Tito Antonio , Margari Vito , Resta Fabrizio , Dhojniku Ilir , Paparella Domenico , Speziale Giuseppe
Published: December 2021

Background

Patients undergoing transcatheter aortic valve replacement (TAVR) usually have multiple comorbidities, such as severely impaired left ventricular function (LVF) and heavily calcified coronary lesions. When they undergo pre-TAVR high-risk percutaneous coronary interventions (HR-PCIs) for severely calcified left main (LM) lesions, potential life-threatening intra-procedural complications associated with the different techniques available to treat calcified lesions can arise. In this setting, mechanical circulatory support proves its usefulness. However, the choice of device can be troublesome.

Case summary

We report two clinical scenarios of intravascular lithotripsy (IVL) for the treatment of heavily calcified LM coronary lesions, wherein peripheral veno-arterial extracorporeal membrane oxygenation (VA-ECMO), alone or combined with an intra-aortic balloon pump (IABP), were used as an upfront strategy to support the procedure. The use of these techniques was particularly effective during multi-vessel HR-PCIs and TAVR, and no complications occurred, which suggested their safety.

Discussion

These cases provide multiple insights into the strategy of using IVL + VA-ECMO, alone or with IABP, to treat heavily calcified LM coronary lesions in patients with severely compromised LVF undergoing TAVR. IVL safely and effectively overcame shortcomings related to other plaque ablation techniques, and VA-ECMO proved to be effective when facing the combination of high-risk coronary and valve interventions.
A Modest Approach to the Customary International Law of Jurisdiction
Authors: Dodge William S
Published: December 2021

This article responds to Cedric Ryngaert’s commentary on the treatment of the customary international law of jurisdiction in the Restatement of the Law (Fourth): The Foreign Relations Law of the United States. With respect to prescriptive jurisdiction, the article explains that the Restatement (Fourth) has not abandoned reasonableness as a rule of customary international law, although its ‘genuine connection’ requirement differs from the interest-balancing approach of the Restatement (Third). With respect to adjudicative jurisdiction, the article explains that the Restatement does not exclude the possibility of limits under customary international law but simply finds that no such limits currently exist, apart from the rules on foreign sovereign immunity. In each case, the Restatement reflects a modest approach to the customary international law of jurisdiction that insists on state practice and opinio juris.
De-noising receiver function data using the unsupervised deep learning approach
Authors: Dalai Bijayananda , Kumar Prakash , Srinu Uppala , Sen Mrinal K
Published: December 2021

The converted wave data (P-to-s or S-to-p), traditionally termed as receiver functions, are often contaminated with noise of different origin that may lead to the erroneous identification of phases and thus influence the interpretations. Here, we utilize an unsupervised deep learning approach called Patchunet to de-noise the converted wave data. We divide the input data into several patches, which are input to the encoder and decoder network to extract some meaningful features. The method de-noises an image patch by patch and utilizes the redundant information on similar patches to obtain the final de-noised results. The method is first tested on a suite of synthetic data contaminated with various amounts of Gaussian and realistic noise and then on the observed data from three permanent seismic stations: HYB (Hyderabad, India), LBTB (Lobatse, Botswana, South Africa) and COR (Corvallis, Oregon, USA). The method works very well even when the signal-to-noise ratio is poor or with the presence of spike noise and deconvolution artifacts. The field data demonstrate the effectiveness of the method for attenuating the random noise especially for the mantle phases, which show significant improvements over conventional receiver function based images.
Canine DUXC: implications for DUX4 retrotransposition and preclinical models of FSHD
Authors: Wong Chao-Jen , Whiddon Jennifer L , Langford Ashlee T , Belleville Andrea E , Tapscott Stephen J
Published: December 2021

Mis-expression of DUX4 in skeletal muscle causes facioscapulohumeral muscular dystrophy (FSHD). Human DUX4 and mouse Dux are retrogenes derived from retrotransposition of the mRNA from the parental DUXC gene. Primates and rodents have lost the parental DUXC gene, and it is unknown whether DUXC had a similar role in driving an early pluripotent transcriptional program. Dogs and other Laurasiatherians have retained DUXC, providing an opportunity to determine the functional similarity to the retrotransposed DUX4 and Dux. Here, we identify the expression of two isoforms of DUXC mRNA in canine testis tissues: one encoding the canonical double homeodomain protein (DUXC), similar to DUX4/Dux, and a second that includes an in-frame alternative exon that disrupts the conserved amino acid sequence of the first homeodomain (DUXC-ALT). The expression of DUXC in canine cells induces a pluripotent program similar to DUX4 and Dux and induces the expression of a similar set of retrotransposons of the ERV/MaLR and LINE-1 families, as well as pericentromeric satellite repeats; whereas DUXC-ALT did not robustly activate gene expression in these assays. Important for preclinical models of FSHD, human DUX4 and canine DUXC show higher conservation of their homeodomains and corresponding binding motifs compared with the conservation between human DUX4 and mouse Dux, and human DUX4 activates a highly similar transcriptional program in canine cells. Together, these findings show that retrotransposition resulted in the loss of an alternatively spliced isoform and that DUXC containing mammals might be good candidates for certain preclinical models ofFSHD.
‘The Greatest Victory’? Challenges and Opportunities for Mediation in Investor-State Dispute Settlement
Authors: de la Rasilla Ignacio
Published: December 2021

This article identifies the rise of mediation as a reaction to the ‘public legitimacy crisis’ experienced by arbitration in investor-State dispute settlement (ISDS) and, more broadly, as a general symptom of the contemporary backlash against international adjudication. It offers an analysis of the nine main challenges that mediation has traditionally faced in ISDS, together with a notice of how recent developments have been contributing to unlocking its underutilized potential. It illustrates the support of numerous States, and in particular of Asian States led by China for dispute prevention and mediation, and provides a critical analysis of some of the limitations of the mediation-related reform options in the agenda of UNCITRAL’s Working Group III including the development of model clauses, a multilateral international investment law advisory centre and a multilateral investment court. The article also examines the recent UNCITRAL secretariat’s guidelines addressing some of the other obstacles faced by mediation in ISDS, including, but not limited to, governance, legislative and policy impediments and the tension between confidentiality in mediation and transparency as a structural goal. The conclusion recaps the main findings of the article and stresses the minimum common denominator quality of mediation as a means to restore balance in a reformed ISDS ‘ecosystem’.