bluuebunny/crossref_metadata_2025 huggingface dataset:
Control the number of skip‐connects to improve robustness of the NAS algorithm
Authors: Zhang Bao Feng , Zhou Guo Qiang
Published: April 2021

Recently, the gradient‐based neural architecture search has made remarkable progress with the characteristics of high efficiency and fast convergence. However, two common problems in the gradient‐based NAS algorithms are found. First, with the increase in the raining time, the NAS algorithm tends to skip‐connect operation, leading to performance degradation and instability results. Second, another problem is no reasonable allocation of computing resources on valuable candidate network models. The above two points lead to the difficulty in searching the optimal sub‐network and poor stability. To address them, the trick of pre‐training the super‐net is applied, so that each operation has an equal opportunity to develop its strength, which provides a fair competition condition for the convergence of the architecture parameters. In addition, a skip‐controller is proposed to ensure each sampled sub‐network with an appropriate number of skip‐connects. The experiments were performed on three mainstream datasets CIFAR‐10, CIFAR‐100 and ImageNet, in which the improved method achieves comparable results with higher accuracy and stronger robustness.
An aggregated deep convolutional recurrent model for event based surveillance video summarisation: A supervised approach
Authors: U. Sreeja M. , Kovoor Binsu C.
Published: April 2021

Surveillance video summarisation is characterised by extracting video segments containing abnormal events from surveillance video footages. Accurate identification of abnormal events from surveillance footages is of paramount importance in surveillance video summarisation. Accordingly, the proposed framework builds an aggregated convolutional recurrent model that can precisely detect the suspicious events in a surveillance footage, by employing a supervised learning which is found to yield better results compared with unsupervised counterparts. The preliminary stage in the model is a multilayer Convolutional Neural Network for frame‐level feature extraction followed by stacked bidirectional Gated Recurrent Unit for sequence‐level feature extraction and classification. Since the video clips used for training are not implicit to surveillance, a block‐based approach for testing on surveillance videos is proposed. The results evaluated on two custom datasets, Streets and Campus, prove that the proposed model produces remarkable results leveraging the properties of bidirectional GRU with supervised learning. Extensive experimental analysis on selection of optimum architecture is conducted which substantiates the significance of stacked bidirectional GRUs over unidirectional ones. Additionally, qualitative results ensure that summaries produced are concise, representative, complete, diverse and informative. Moreover, comparison of the performance of the proposed model with state of the art certainly proves the superiority of the proposed model.
60‐ghz wideband circularly polarized antenna array based on TE340‐mode SIC and sequential rotation feeding technique
Authors: Zhu Yuefang , Qi Zihang , Zhu Hua , Li Xiuping
Published: April 2021

The authors propose a 4 × 4 circularly polarized (CP) antenna array with wide impedance bandwidth and axial‐ratio (AR) bandwidth and design the same for 60‐GHz applications. The overall structure of the proposed antenna array consists of a cavity‐back circular patch array and two layer feed‐networks. The upper feed‐network is with four TE340 high‐order mode substrate integrated cavities (SIC). Fed with SIC, circular patches with a pair of 42°‐inclined slits can achieve circular polarization. In order to improve the AR bandwidth and gain performance, the substrate integrated waveguide (SIW) sequential rotation feeding technique is utilized in the lower feed‐network. For proof of concept, the 4 × 4 array is fabricated and measured. Measured results show that −10‐dB impedance bandwidth of the proposed antenna array is 27.2% from 52 to 68.4 GHz and 3‐dB AR bandwidth is 18.9% from 55.7 to 67.3 GHz. Furthermore, the 3‐dB gain bandwidth is 26.2% from 53 to 69 GHz with a peak gain reaching 19.3 dBic at 62 GHz.
Analysis of double‐Xi‐shaped millimetre‐wave patch antenna backed by a high‐order‐mode cavity using characteristic mode design
Authors: Feng Botao , Chen Junlong , Sim Chow‐Yen‐Desmond
Published: April 2021

The authors propose an innovative double‐Xi‐shaped Chinese character artistic antenna backed by a high‐order‐mode cavity for 5G millimetre‐wave (mm‐wave) applications. The initial double‐Xi‐shaped microstrip antenna element is designed by using characteristic mode theory, and stable gain can be obtained across the whole 5G mm‐wave frequency band. By employing a slotted cavity with TE230 high‐order‐mode to excite 2×2 antenna subarray, a high gain of 13.2 ± 0.8 dBi and a high isolation better than 45 dB without additional feeding networks can be simultaneously achieved. To further improve the gain for reliable transmission, a 4×4 dual linearly polarised (LP) antenna array is also designed and fabricated. Measured results show that a wide frequency bandwidth of 11.45% (24.7–27.7 GHz) with a peak gain of 19.2 dBi and a high isolation of 33 dB is realised for the dual LP antenna array. The proposed method provides a simple and efficient prediction‐theory way to design artistic antenna for the first time, which solves the problem of designing specific‐shaped antenna without theoretical support.
The image edge model
Authors: Erraji Armin , Stienen Jonas , Vorländer Michael
Published: April 2021

Noise from traffic, industry and neighborhood is a prominent feature in urban environments. In these environments, sound reaches receiver points through reflections and diffractions. Real-time auralization of outdoor scenarios is a common goal for presenting sound characteristics in a realistic and intuitive fashion. Challenges in this attempt can be identified on many levels, however the most prominent part is sound propagation simulation. Geometrical acoustics has become the de-facto standard for the prediction of acoustic propagation in a virtual scenario. A considerable difficulty is the determination of the diffracted sound field component, because it is a wave effect that must be be explicitly integrated into the search algorithm of valid propagation paths. A deterministic solution to this problem is implemented that establishes propagation paths with an arbitrary constellation of far-field interactions at geometrical boundaries, i.e. reflecting surfaces and diffracting edges in large distance to each other. The result is an open-source code algorithm for propagation paths that follows the wave front normal and assembles metadata required for further acoustic modelling, such as incoming and outgoing angles, reflection material and geometrical details for the construction of the diffracting wedge. Calculation times are outlined and a proof of concept is presented that describes the employment of the propagation algorithm as well as the determination of an acoustic transfer function based on the input of the intermediate path representation. Future research will focus on prioritization of path contributions according to physical and psychoacoustical culling schemes.
Renewable energy: a bibliometric analysis
Authors: Rosokhata Anna , Minchenko Mariia , Khomenko Liliya , Chygryn Olena
Published: April 2021

The aims of this paper are to identify existing research on renewable energy; identify the most influential publications, authors, organizations to understand the research areas. The paper is centered on the bibliometric analysis based on the Web of Science database for the key phrase’ renewable energy’ in the article title until 2020. We analyzed the publications about renewable energy by years, by research areas, by geography, by research organizations and research sponsors, by journals, by citations of journals, authors, publications, co-occurrence by keywords. Analysis of the most cited publications and authors, analysis of cooccurrence by keywords was performed using VOSviewer. We performed hierarchical cluster analysis, and clusters were selected using VOSviewer. We found 17805 scientific publications on renewable energy published in scientific journals (51.7% of publications were published during 2016-2020). The most popular research areas are energy fuels, engineering, science technology, environmental sciences, ecology, and business economics. The majority of papers was published by the scientists from the United States, China, and India. In addition, we identified six main research clusters. They are related to an optimizer, renewable energy, biomass, co2 emissions, model, desalination. Conclusions: This analysis confirmed the author’s hypothesis about the definition of new scientific horizons of renewable energy research. Our results can help scientists interested in renewable energy looking for research funding and research project risks based on renewable energy.
Economic analysis of alternative energy development in Nagorno-Karabakh and surrounding regions
Authors: Guliyeva Aida , Mammadzada Parvin , Mamedov Turan
Published: April 2021

This paper studies the main opportunities for stimulating investments in the alternative energy development through implementation of state plans for creation and support of favourable socio-economic conditions in Nagorno-Karabakh and 7 surrounding regions. Due to the longevity of projects on renewable energy sources, as well as the traditional financing of infrastructure projects, it is extremely important that political and economic interests were protected by law. At the present time there are active project work on development and optimisation of energy sector, and therefore understanding of basic principles is quite diverse in public and private sectors. Main conclusions and recommendations are developed and presented for economic development of renewable energy sources (RES) in Nagorno-Karabakh and surrounding regions of Azerbaijan.
University 4.0 within the context of the sustainable development of higher education
Authors: Gorina Larisa , Polyakova Ekaterina
Published: April 2021

The process of development of universities from the places where medieval elites met to conduct alliances and partnerships to the modern biotechnological and digital institutions of higher education, research and business took several centuries and went through four main stages. This paper describes the role and the place of the University 4.0 within the context of the sustainable development of higher education in the 21stcentury. We show that University 4.0 is designed to promote the technology industry through partnerships that support research, marketing, workforce development, as well as entrepreneurship. In keeping with the cooperative nature efforts directed and driven by the policy-makers and relevant stakeholders need to be dedicated to promoting modern universities as hub for the development of intelligent, connected technologies and services that would lead to the sustainable development of higher education that would reflect the challenges of our time.
Green brands and sustainable entrepreneurship
Authors: Freze Tatiana , Nurova Oksana
Published: April 2021

Our paper focuses on the development of green brands as the part of the sustainable environmental management. It demonstrates that the main goal of the green technology is to focus on the specific interface of environmentally-friendly and sustainable technology, innovation and business development. It is building solutions that promote the development of clean energy, energy efficiency, renewable energy and efficient technologies. Moreover, it makes it clear that one should also underline the importance of sustainable transport, sustainable agriculture and sustainable urban development within this context. In addition, the paper focuses on the green marketing and environmental management as the parts of the sustainable entrepreneurship of the 21stcentury. It becomes clear that environmental benefits of products and services should be highlighted and advertised by business companies in order to sustain their position on the globalized markets with severe competition.
A reliability analysis method for earthquake resistance of large complex building structure
Authors: Xiao Yanjie , Zhang Xun'an , Xue Ronggang
Published: April 2021

The seismic reliability calculation of complex building structures requires a lot of simulation analysis and therefore the calculation cost is high. Fitting performance function with surrogate model can improve computational efficiency, but how to ensure the calculation accuracy while improving the reliability analysis efficiency of the engineering structure is a problem worthy of study. This paper proposes a Kriging-based reliability analysis method, which establishes the Kriging surrogate model with fewer calculations of the performance function, improves the accuracy of the surrogate model of performance function by infill-sampling, and obtains the approximate failure probability combined with Monte Carlo simulation. Two numerical examples are analyzed; the results show that this method is efficient and accurate. The method is applied to the seismic reliability calculation of mega-sub controlled structural system, in which the randomness of structure and seismic action is considered. The application results show that it is an effective method for reliability analysis of complex building structures.
UAV attitude calculation algorithm based on acceleration correction model
Authors: Liu Xuhang , Liu Xiaoxiong , Zhang Weiguo , Yang Yue
Published: April 2021

In order to improve the accuracy of attitude of unmanned aerial vehicle (UAV) navigation system in dynamic environment, an attitude calculation algorithm based on acceleration correction model is proposed. First, the acceleration correction model is established to calculate the estimated non-gravitational acceleration and external non-gravitational acceleration to modify the output value of the accelerometer, which reduces the influence of non-gravitational acceleration on the attitude calculation in dynamic environment. Then, the attitude calculation model based on Kalman filter is built, attitude angle calculated by corrected acceleration and magnetometer as measurement of filtering model, and the attitude calculation algorithm based on the acceleration correction model is designed. The experimental results show that the algorithm can reduce the interference of non-gravitational acceleration to attitude calculation, which avoids attitude angle divergence of UAV navigation system in dynamic environment, and improves the accuracy and anti-interference ability of UAV navigation system in dynamic environment.
Dual-rotor misalignment fault quantitative identification based on DBN and improved D-S evidence theory
Authors: Dalian Yang , Fanyu Zhang , Jingjing Miao , Hongxian Zhang , Renjie Li , Jie Tao
Published: April 2021

Misalignment fault is the main factor that affects the normal running of dual-rotor system. Quantitative identification the misalignment fault is an important way to ensure the safe and stable service of the dual-rotor system, while the identification accuracy of traditional methods is low. Aiming at the above problems, this paper proposed a dual-rotor misalignment fault quantitative identification method based on DBN and D-S evidence theory improved by mutual information measure (MIMD-S). Seven groups experiments were conducted and several vibration signals were collected. By comparing it with the traditional methods D-S, and Pignistic improved D-S (PD-S) evidence theory, the results show that the method proposed in this paper improves the accuracy of the misalignment fault quantitative identification of the dual-rotor, the identification error rate was only 0.36%.
Acute gastrointestinal bleeding: results from the prospective German electronic registry of nearly 11 000 endoscopies (ALGK GI-bleeding registry)
Authors: Fischbach Wolfgang , Klassert Christine , Schilling Dieter , Sarah Kordian , Schneider Thomas , Cossmann Theresa , Frieling Thomas
Published: April 2021

Background and study aims Gastrointestinal bleeding is frequently observed in the German population. However, recent epidemiological data are not available. This study aimed to elucidate gastrointestinal bleeds under real-life conditions in 3 German hospitals. By using a standardized electronic documentation system, a large number of consecutive endoscopies could be established, thus offering representative data.

Patients and methods From June 2017 to December 2018, all upper and lower gastrointestinal tract endoscopies were recorded consecutively in the 3 hospitals. The electronic documentation system used included a case report form for storing data on bleeding as obligatory input for completion of the endoscopy report. In the case of gastrointestinal bleeding, specific data on the bleeding source and intensity, as well as individual characteristics, were documented.

Results A total of 10 948 consecutive endoscopies were recorded, and 10 904 could be analyzed. Signs of gastrointestinal bleeding were found in 863 patients (7.9 % of all endoscopies performed), 538 patients with an intake of hemostasis-affecting drugs, and 325 patients without (62.3 % and 37.7 %, respectively). Platelet inhibitors and anticoagulants were the most frequently used hemostasis-affecting medication. There was a significant increase in age from patients without bleeding (median 68.5 years) to patients with bleeding (73.5 years) and to patients with bleeding who took hemostasis-affecting medication (80.4 years). Among the patients, 257 (29.8 %) and 606 (70.2 %) presented with major and minor bleeding, respectively.

Conclusions About 8 % of all patients undergoing upper or lower gastrointestinal endoscopy reveal signs of bleeding. A considerable number are older patients taking hemostasis-affecting drugs.
Calcium fluoride as high-k dielectric for 2D electronics
Authors: Wen Chao , Lanza Mario
Published: April 2021

Calcium fluoride is a dielectric material with a wide bandgap (∼12.1 eV) and a relatively high dielectric constant (∼6.8) that forms a van der Waals interface with two-dimensional (2D) materials, meaning that it contains a very low amount of defects. Thin calcium fluoride films can be synthesized using multiple techniques that are scalable to the wafer level, including molecular beam epitaxy, atomic layer deposition, and chemical vapor deposition. However, the consolidation of calcium fluoride as dielectric for 2D electronics requires overcoming some fundamental challenges related to material quality and integration, as well as carrying out advanced characterization and computational studies to evaluate its real potential. Here, we review the status of calcium fluoride dielectric films in terms of material synthesis, fundamental electrical properties, and future applications; we also discuss the most important challenges of calcium fluoride integration in 2D materials–based, solid-state nano/micro-electronic devices, and propose several potential routes to overcome them. Our manuscript may serve as a useful guide for other scientists working on 2D electronics in general, and provides a clear pathway for calcium fluoride research in the future.
Exact solution of partial differential equations for the creation of jet-like flows in plasmas and neutral fluids
Authors: Saleem H.
Published: April 2021

An exact solution of two fluid ideal classical plasma equations is presented which shows that the one-dimensional jet-like axial outflow and two-dimensional magnetic field are generated simultaneously by the density and temperature gradients of both electrons and ions in cylindrical geometry. Particular profiles of density function ψ=ln n¯ (where n¯ is normalized by some constant density N0) and temperatures Tj (for j=e,i) have to be chosen to obtain an exact solution of the complicated nonlinear partial differential equations. But this is a natural analytical exact solution of the ideal two fluid plasma equations. The basic mechanism presented here explains the creation of plasma jet-like flows along with magnetic fields in astrophysical environments such as young stellar objects, active galactic nuclei, solar spicules, flares, and coronal loops. The theoretical model is also applicable to laser induced plasma where magnetic field and plasma ablation are produced simultaneously. An exact analytical solution of ideal neutral fluid equations is also presented which shows that the jet-like outflows can be generated by the density and temperature gradients in such systems.
Correlation of high-field and zero- to ultralow-field NMR properties using 2D spectroscopy
Authors: Zhukov Ivan V. , Kiryutin Alexey S. , Yurkovskaya Alexandra V. , Blanchard John W. , Budker Dmitry , Ivanov Konstantin L.
Published: April 2021

The field of zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) is currently experiencing rapid growth, owing to progress in optical magnetometry and attractive features of ZULF-NMR such as low hardware cost and excellent spectral resolution achieved under ZULF conditions. In this work, an approach is proposed and demonstrated for simultaneous acquisition of ZULF-NMR spectra of individual 13C-containing isotopomers of chemical compounds in a complex mixture. The method makes use of fast field cycling such that the spin evolution takes place under ZULF conditions, whereas signal detection is performed in a high-field NMR spectrometer. This method has excellent sensitivity, also allowing easy assignment of ZULF-NMR spectra to specific analytes in the mixture. We demonstrate that the spectral information is the same as that given by ZULF-NMR, which makes the method suitable for creating a library of ZULF-NMR spectra of various compounds and their isotopomers. The results of the field-cycling experiments can be presented in a convenient way as 2D-NMR spectra with the direct dimension giving the high-field 13C-NMR spectrum (carrying the chemical-shift information) and the indirect dimension giving the ZULF-NMR spectrum (containing information about proton–carbon J-couplings). Hence, the method can be seen as a variant of heteronuclear J-resolved spectroscopy, one of the first 2D-NMR techniques.
Multilevel summation for periodic electrostatics using B-splines
Authors: Kaya Hüseyin , Hardy David J. , Skeel Robert D.
Published: April 2021

Fast methods for calculating two-body interactions have many applications, and for molecular science and cosmology, it is common to employ periodic boundary conditions. However, for the 1/r potential, the energy and forces are ill-defined. Adopted here is the model given by the classic Ewald sum. For the fast calculation of two-body forces, the most celebrated method is the fast multipole method and its tree-code predecessor. However, molecular simulations typically employ mesh-based approximations and the fast Fourier transform. Both types of methods have significant drawbacks, which, in most respects, are overcome by the less well-known multilevel summation method (MSM). Presented here is a realization of the MSM, which can be regarded as a multilevel extension of the (smoothed) particle mesh Ewald (PME) method, but with the Ewald softening replaced by one having a finite range. The two-level (single-grid) version of MSM requires fewer tuning parameters than PME and is marginally faster. Additionally, higher-level versions of MSM scale well to large numbers of processors, whereas PME and other two-level methods do not. Although higher-level versions of MSM are less efficient on a single processor than the two-level version, evidence suggests that they are more efficient than other methods that scale well, such as the fast multipole method and tree codes.
Modeling of combined effects of surface roughness and blowing for Reynolds-averaged Navier–Stokes turbulence models
Authors: Marchenay Y. , Chedevergne F. , Olazabal Loumé M.
Published: April 2021

A new modeling strategy adapted to Reynolds-averaged Navier–Stokes turbulence models is proposed to predict combined effects of roughness and blowing boundary conditions. First, an analysis of experimental data is presented, leading to a specific description of the velocity profile in the logarithmic region of transpired turbulent boundary layers over rough walls. This analysis points out the deficiencies of existing roughness corrections to predict the effect of blowing in the presence of surface roughness. Indeed, these corrections tend to underestimate skin friction coefficients and Stanton numbers with the addition of blowing. The failure of existing models derives from an inaccurate estimation of the velocity shift of the logarithmic law given by roughness corrections. Concretely, roughness corrections underestimate the apparent velocity shift of the logarithmic law with blowing. To recover the expected law of the wall, an additional contribution on the velocity shift, characterizing blowing/roughness interactions, is integrated to standard roughness corrections. To that end, a modification of the equivalent sand grain height, adapted to k−ω based turbulence models, is proposed to take blowing effects into account. Furthermore, an extension of Aupoix's thermal correction [B. Aupoix, Int. J. Heat Fluid Flow 56, 160–171 (2015)] to blowing is presented to predict combined thermal effects of roughness and blowing. The assessment of the proposed corrections is performed using k−ω shear stress transport model on a large set of experimental data and proves the relevance of the strategy for incompressible and compressible turbulent boundary layers.
A new class of focusing crystal shapes for Bragg spectroscopy of small, point-like, x-ray sources in laser produced plasmas
Authors: Bitter M. , Pablant N. , Hill K. W. , Gao Lan , Kraus B. , Efthimion P. C. , Delgado-Apericio L. , Stratton B. , Schneider M. , Coppari F. , Kauffman R. , MacDonald M. J. , MacPhee A. , Ping Y. , Stoupin S. , Thorn D.
Published: April 2021

This paper describes a new class of focusing crystal forms for the x-ray Bragg crystal spectroscopy of small, point-like, x-ray sources. These new crystal forms are designed with the aid of sinusoidal spirals, a family of curves, whose shapes are defined by only one parameter, which can assume any real value. The potential of the sinusoidal spirals for the design x-ray crystal spectrometers is demonstrated with the design of a toroidally bent crystal of varying major and minor radii for measurements of the extended x-ray absorption fine structure near the Ta-L3 absorption edge at the National Ignition Facility.
Identification of time scales of the violation of the Stokes–Einstein relation in Yukawa liquids
Authors: Ghannad Zahra
Published: April 2021

We investigate the origin of the violation of the Stokes–Einstein (SE) relation in two-dimensional Yukawa liquids. Using comprehensive molecular dynamics simulations, we identify the time scales supporting the violation of the SE relation D∝(η/T)−1, where D is the self-diffusion coefficient and η is the shear viscosity. We first compute the self-intermediate scattering function Fs(k,t), the non-Gaussian parameter α2, and the autocorrelation function of the shear stress Cη(t). The time scales obtained from these functions include the structural relaxation time τα, the peak time of the non-Gaussian parameter τα2, and the shear stress relaxation time τη. We find that τη is coupled with D for all temperatures indicating the SE preservation; however, τα and τα2 are decoupled with D at low temperatures indicating the SE violation. Surprisingly, we find that the origins of this violation are related to the non-exponential behavior of the autocorrelation function of the shear stress and non-Gaussian behavior of the distribution function of particle displacements. These results confirm dynamic heterogeneity that occurs in two-dimensional Yukawa liquids that reflect the presence of regions in which dust particles move faster than the rest when the liquid cools to below the phase transition temperature.
Multi-layer Gaussian-based multi-configuration time-dependent Hartree (ML-GMCTDH) simulations of ultrafast charge separation in a donor–acceptor complex
Authors: Di Maiolo Francesco , Worth Graham A. , Burghardt Irene
Published: April 2021

We report on first applications of the Multi-Layer Gaussian-based Multi-Configuration Time-Dependent Hartree (ML-GMCTDH) method [Römer et al., J. Chem. Phys. 138, 064106 (2013)] beyond its basic two-layer variant. The ML-GMCTDH scheme provides an embedding of a variationally evolving Gaussian wavepacket basis into a hierarchical tensor representation of the wavefunction. A first-principles parameterized model Hamiltonian for ultrafast non-adiabatic dynamics in an oligothiophene–fullerene charge transfer complex is employed, relying on a two-state linear vibronic coupling model that combines a distribution of tuning type modes with an intermolecular coordinate that also modulates the electronic coupling. Efficient ML-GMCTDH simulations are carried out for up to 300 vibrational modes using an implementation within the QUANTICS program. Excellent agreement with reference ML-MCTDH calculations is obtained.
Misinformation and public opinion of science and health: Approaches, findings, and future directions
Authors: Cacciatore Michael A.
Published: April 2021

A summary of the public opinion research on misinformation in the realm of science/health reveals inconsistencies in how the term has been defined and operationalized. A diverse set of methodologies have been employed to study the phenomenon, with virtually all such work identifying misinformation as a cause for concern. While studies completely eliminating misinformation impacts on public opinion are rare, choices around the packaging and delivery of correcting information have shown promise for lessening misinformation effects. Despite a growing number of studies on the topic, there remain many gaps in the literature and opportunities for future studies.
Measuring the news and its impact on democracy
Authors: Watts Duncan J. , Rothschild David M. , Mobius Markus
Published: April 2021

Since the 2016 US presidential election, the deliberate spread of misinformation online, and on social media in particular, has generated extraordinary concern, in large part because of its potential effects on public opinion, political polarization, and ultimately democratic decision making. Recently, however, a handful of papers have argued that both the prevalence and consumption of “fake news” per se is extremely low compared with other types of news and news-relevant content. Although neither prevalence nor consumption is a direct measure of influence, this work suggests that proper understanding of misinformation and its effects requires a much broader view of the problem, encompassing biased and misleading—but not necessarily factually incorrect—information that is routinely produced or amplified by mainstream news organizations. In this paper, we propose an ambitious collective research agenda to measure the origins, nature, and prevalence of misinformation, broadly construed, as well as its impact on democracy. We also sketch out some illustrative examples of completed, ongoing, or planned research projects that contribute to this agenda.
Misinformation in and about science
Authors: West Jevin D. , Bergstrom Carl T.
Published: April 2021

Humans learn about the world by collectively acquiring information, filtering it, and sharing what we know. Misinformation undermines this process. The repercussions are extensive. Without reliable and accurate sources of information, we cannot hope to halt climate change, make reasoned democratic decisions, or control a global pandemic. Most analyses of misinformation focus on popular and social media, but the scientific enterprise faces a parallel set of problems—from hype and hyperbole to publication bias and citation misdirection, predatory publishing, and filter bubbles. In this perspective, we highlight these parallels and discuss future research directions and interventions.
The narrative truth about scientific misinformation
Authors: Dahlstrom Michael F.
Published: April 2021

Science and storytelling mean different things when they speak of truth. This difference leads some to blame storytelling for presenting a distorted view of science and contributing to misinformation. Yet others celebrate storytelling as a way to engage audiences and share accurate scientific information. This review disentangles the complexities of how storytelling intersects with scientific misinformation. Storytelling is the act of sharing a narrative, and science and narrative represent two distinct ways of constructing reality. Where science searches for broad patterns that capture general truths about the world, narratives search for connections through human experience that assign meaning and value to reality. I explore how these contrasting conceptions of truth manifest across different contexts to either promote or counter scientific misinformation. I also identify gaps in the literature and identify promising future areas of research. Even with their differences, the underlying purpose of both science and narrative seeks to make sense of the world and find our place within it. While narrative can indeed lead to scientific misinformation, narrative can also help science counter misinformation by providing meaning to reality that incorporates accurate science knowledge into human experience.
Experimental evidence of memory-based foraging decisions in a large wild mammal
Authors: Ranc Nathan , Moorcroft Paul R. , Ossi Federico , Cagnacci Francesca
Published: April 2021

Significance

Understanding how animals respond to changes in resource availability is central to ecological research and to designing effective wildlife conservation and management strategies. To date, little research has been conducted on the cognitive mechanisms—memory or perception—by which large mammals make foraging decisions in nature. By combining a mechanistic cognitive model with a field manipulation of food availability, we show that roe deer rely on memory, not perception, to track the spatial and temporal changes in resource availability in their local environment. Our approach allows us to quantify memory use and to successfully predict how individuals will respond to future changes.
Simplicial gravity with coordinates
Authors: D’Adda Alessandro
Published: April 2021

We present a formulation of Regge calculus where arbitrary coordinates are associated to each vertex of the simplicial complex and the fundamental degrees of freedom are given by the metric g

μν
(α) on each simplex α. The lengths of the edges, which are the usual degrees of freedom of Regge calculus, are thus determined and are left invariant under arbitrary transformations of the discrete set of coordinates, provided the metric transforms accordingly. Invariance under coordinate transformations entails tensor calculus and our formulation then follows closely the usual formalism of the continuum theory. This includes a definition of partial derivative which stems from a generalization to simplicial lattices of the symmetric finite difference operator on a cubic lattice. The definitions of parallel transport, Christoffel symbol, covariant derivatives and Riemann curvature tensor follow in a rather natural way establishing a kind of dictionary between continuum and simplicial lattice quantities. In this correspondence Einstein action becomes Regge action with the deficit angle θ replaced by sin θ. The correspondence with the continuum theory can be extended to actions with higher powers of the curvature tensor, to the vielbein formalism and to the coupling of gravity with matter fields (scalars, fermionic fields including spin 3/2 fields and gauge fields) which are then determined unambiguously and discussed in the paper. An action on the simplicial lattice for N = 1 supergravity in four dimensions is derived in this context. Another relavant result is that Yang–Mills actions on a simplicial lattice consist, even in absence of gravity, of two plaquettes terms, unlike the one plaquette Wilson action on the hypercubic lattice. An attempt is also made to formulate a discrete differential calculus to include differential forms of higher order and the gauging of free differential algebras in this scheme. However this leads to form products that do not satisfy associativity and distributive law with respect to the d operator. A proper formulation of theories that contain higher order differential forms in the context of Regge calculus is then still lacking.
Quantum nondemolition measurement based generation of entangled states in two Bose–Einstein condensates
Authors: Aristizabal-Zuluaga Juan E , Skobleva Iuliia , Richter Lars , Ji Yangxu , Mao Yuping , Kondappan Manikandan , Ivannikov Valentin , Byrnes Tim
Published: April 2021

We theoretically study a scheme for generating entanglement between two Bose–Einstein condensates (BECs). The scheme involves placing two BECs in the path of a Mach–Zehnder interferometer, where the coherent light interacts with the atoms due to a quantum nondemolition Hamiltonian. In contrast to standard approaches where a Holstein–Primakoff approximation is used, we use an exact wavefunction approach where the atoms can be initialized in an arbitrary state and the light–atom interaction times can be arbitrary. In the short time regime, it is possible to construct a very simple approximate theory for the overall effect of the scheme: amplitudes in the superposition between the two BECs with unequal spin eigenvalues are damped. We analyze the types of correlations, entanglement, Einstein–Podolsky–Rosen (EPR) steering, and Bell correlations that are produced and show that the state is similar to a spin-EPR state. Using a two-pulse sequence the correlations can be dramatically improved, where the state further approaches a spin-EPR state.
High-yield thermalized positronium at room temperature emitted by morphologically tuned nanochanneled silicon targets
Authors: Mariazzi S , Caravita R , Zimmer C , Rienäcker B , Camper A , Belov A , Bonomi G , Brusa R S , Castelli F , Consolati G , Doser M , Gjersdal H , Glöggler L T , Guatieri F , Haider S , Matveev V , Nebbia G , Nedelec P , Pagano D , Penasa L , Petracek V , Prelz F , Povolo L , Rhøne O M , Rotondi A , Sandaker H , Zurlo N
Published: April 2021

Nanochanneled silicon targets with high positron/positronium (Ps) conversion rate and efficient Ps cooling were produced. Morphological parameters of the nanochannels, such as their diameter and length, were adjusted to get a large fraction of thermalized Ps at room temperature being emitted into vacuum. Ps cooling measurements were conducted combining single-shot positron annihilation lifetime spectroscopy and Doppler spectroscopy of the 13S → 23P transition. 2γ–3γ annihilation ratio measurements were also performed to estimate the positron/Ps conversion efficiency. In a converter with nanochannel diameter of 7–10 nm and depth of 3.89 μm, ∼28% of implanted positrons with an energy of 3.3 keV was found to be emitted as Ps with a transverse kinetic energy of 11 ± 2 meV. The reduction of the nanochannels depth to 1.13 μm, without changing the nanochannel diameter, was found to result in a less efficient cooling, highlighting the presence of Ps reflection from the bottom end of nanochannels.
Automated assessment of a kinetic database for fcc Co–Cr–Fe–Mn–Ni high entropy alloys
Authors: Abrahams Katrin , Zomorodpoosh Setareh , Khorasgani Ahmadreza Riyahi , Roslyakova Irina , Steinbach Ingo , Kundin Julia
Published: April 2021

The development of accurate kinetic databases by parametrizing the composition and temperature dependence of elemental atomic mobilities, is essential for correct multicomponent calculations and simulations. In this work the automated assessment procedure for the establishment of CALPHAD-type kinetic databases is proposed, including the storage of raw data and assessment results, automatic weighting of data, parameter selection and automated reassessments. This allows the establishment of reproducible up-to-date databases. The proposed software, written in python, is applied to the assessment of a kinetic database for the fcc Co–Cr–Fe–Mn–Ni high entropy alloy using only tracer diffusion data for a sharp separation of thermodynamic and kinetic data. The established database is valid for the whole composition range of the five-component high entropy alloy.
MOF@MnO2 nanocomposites prepared using in situ method and recyclable cholesterol oxidase–inorganic hybrid nanoflowers for cholesterol determination
Authors: Xu Dawei , Li Cong , Zi Yuqiu , Jiang Dafeng , Qu Fei , Zhao Xian-En
Published: April 2021

In this work, through the in situ growth of MnO2 nanosheets on the surface of terbium metal–organic frameworks (Tb–MOFs), MOF@MnO2 nanocomposites are prepared and the fluorescence of Tb–MOFs is quenched significantly by MnO2. Additionally, the hybrid nanoflowers are self-assembled by cholesterol oxidase (ChOx) and copper phosphate (Cu3(PO4)2·3H2O). Then a new strategy for cholesterol determination is developed based on MOF@MnO2 nanocomposites and hybrid nanoflowers. Cholesterol is oxidized under the catalysis of hybrid nanoflowers to yield H2O2, which further reduces MnO2 nanosheets into Mn2+. Hence, the fluorescence recovery of Tb–MOFs is positively correlated to the concentration of cholesterol in the range of 10 to 360 μM. The limit of detection (LOD) of cholesterol is 1.57 μM. On the other hand, the hierarchical and confined structure of ChOx–inorganic hybrid nanoflowers greatly improve the stability of the enzyme. The activity of hybrid nanoflowers remains at a high level for one week when stored at room temperature. Moreover, the hybrid nanoflowers can be collected by centrifugation and reused. The activity of hybrid nanoflowers can continue at a high level for five cycles of determination. Therefore, it can be concluded that the hybrid nanoflowers are more stable and more economic than free enzymes, and they show a similar sensitivity and specificity to cholesterol compared with free ChOx. Finally, this strategy has been further validated for the determination of cholesterol in serum samples with satisfactory recoveries.
Generalized collisional fluid theory for multi-component, multi-temperature plasma using the linearized Boltzmann collision operator for scrape-off layer/edge applications
Authors: Raghunathan M , Marandet Y , Bufferand H , Ciraolo G , Ghendrih Ph , Tamain P , Serre E
Published: April 2021

Grad’s method is used on the linearized Boltzmann collision operator to derive the most general expressions for the collision coefficients for a multi-component, multi-temperature plasma up to rank-2. In doing so, the collision coefficients then get expressed as series sum of pure coefficients of temperature and mass ratios multiplied by the cross-section dependent Chapman–Cowling integrals. These collisional coefficients are compared to previously obtained coefficients by Zhdanov (2002 Transport Processes in Multicomponent Plasma (London: Taylor and Francis)) for 13N-moment multi-temperature scheme. First, the differences in coefficients are compared directly, and then the differences in first approximation to viscosity and friction force are compared. For the 13N-moment multi-temperature coefficients, it is found that they behave reasonably similarly for small temperature differences, but display substantial differences in the coefficients when the temperature differences are high, both for the coefficients and for viscosity and friction force values. Furthermore, the obtained coefficients are compared to the 21N-moment single-temperature approximation provided by Zhdanov et al, and it is seen that the differences are higher than the 13N-moment multi-temperature coefficients, and have substantial differences even in the vicinity of equal temperatures, especially for the viscosity and friction force calculations.
Effects of a coherent mode on the redistribution of divertor particle flux in HL-2A H-mode plasmas
Authors: Wu N , Cheng J , Yan L W , Huang Z H , Xu J Q , Wang W C , Ke R , Yang Z C , Ji X Q , Liu L , He X X , Jiang M , Wen J , Miao X G , Zhong W L , Yu L M , Gao J M , Dong Y B , Shi Z B , Liu Y , Yang Q W , Dong J Q , Xu M
Published: April 2021

The effects of a coherent mode (CM) at a frequency of f = 13–16 kHz on the redistribution of divertor particle flux have been studied in HL-2A H-mode plasmas using multiple diagnostics. The experimental results demonstrate that a CM localized at the middle of the pedestal results in outward particle transport, limiting the growth of the pedestal density gradient in the recovery phase of the pedestal, leading to a substantial increase in the localized particle flux striking the outer divertor target, which clearly deviates from the primary peak at the strike point. These observations indicate that the CM might play a crucial role in redistributing the divertor particle flux, which is important for understanding and controlling the divertor heat flux in future fusion-relevant devices.
The Cosmological Optical Theorem
Authors: Goodhew Harry , Jazayeri Sadra , Pajer Enrico
Published: April 2021

The unitarity of time evolution, or colloquially the conservation of probability, sits at the heart of our descriptions of fundamental interactions via quantum field theory. The implications of unitarity for scattering amplitudes are well understood, for example through the optical theorem and cutting rules. In contrast, the implications for in-in correlators in curved spacetime and the associated wavefunction of the universe, which are measured by cosmological surveys, are much less transparent. For fields of any mass in de Sitter spacetime with a Bunch-Davies vacuum and general local interactions, which need not be invariant under de Sitter isometries, we show that unitarity implies an infinite set of relations among the coefficients ψ
n
of the wavefunction of the universe with n fields, which we name Cosmological Optical Theorem. For contact diagrams, our result dictates the analytic structure of ψ
n
and strongly constrains its form. For example, any correlator with an odd number of conformally-coupled scalar fields and any number of massless scalar fields must vanish. For four-point exchange diagrams, the Cosmological Optical Theorem yields a simple and powerful relation between ψ3 and ψ4, or equivalently between the bispectrum and trispectrum. As explicit checks of this relation, we discuss the trispectrum in single-field inflation from graviton exchange and self-interactions. Moreover, we provide a detailed derivation of the relation between the total-energy pole of cosmological correlators and flat-space amplitudes. We provide analogous formulae for sub-diagram singularities. Our results constitute a new, powerful tool to bootstrap cosmological correlators.