bluuebunny/crossref_metadata_2025_split huggingface dataset:
A review on geometric formulations for classical field theory: the Bonzom–Livine model for gravity
Authors: Berra-Montiel Jasel , Molgado Alberto , Rodríguez-López Ángel 
Published: April 2021

Abstract
Motivated by the study of physical models associated with general relativity, we review some finite-dimensional, geometric and covariant formulations that allow us to characterize in a simple manner the symmetries for classical field theory by implementing an appropriate fibre-bundle structure, either at the Lagrangian, the Hamiltonian multisymplectic or the polysymplectic levels. In particular, we are able to formulate Noether’s theorems by means of the covariant momentum maps and to systematically introduce a covariant Poisson–Hamiltonian framework. Also, by focusing on the space plus time decomposition for a generic classical field theory and its relation to these geometric formulations, we are able to successfully recover the gauge content and the true local degrees of freedom for the theory. In order to illustrate the relevance of these geometric frameworks, we center our attention to the analysis of a model for three-dimensional theory of general relativity that involves an arbitrary Immirzi-like parameter. At the Lagrangian level, we reproduce the field equations of the system which for this model turn out to be equivalent to the vanishing torsion condition and the Einstein equations. We also concentrate on the analysis of the gauge symmetries of the system in order to obtain the Lagrangian covariant momentum map associated with the theory and, consequently, its corresponding Noether currents. Next, within the Hamiltonian multisymplectic approach, we aim our attention to describing how the gauge symmetries of the model yield covariant canonical transformations on the covariant multimomenta phase-space, thus giving rise to the existence of a covariant momentum map. Besides, we analyze the physical system under consideration within the De Donder–Weyl canonical theory implemented at the polysymplectic level, thus establishing a relation from the covariant momentum map to the conserved currents of the theory within this covariant Hamiltonian approach. Finally, after performing the space plus time decomposition of the space-time manifold, and taking as a starting point the Hamiltonian multisymplectic formulation, we are able to recover both the extended Hamiltonian and the gauge structure content that characterize the gravity model of our interest within the instantaneous Dirac–Hamiltonian formulation.
Photoelectron spectra of shake-up processes from the 2p subshell of sodium atoms in the excited states 2p
63p
Authors: Liu Xiaobin , Shi Yinglong , Li Xiangbin , Lu Feiping , Wang Yuping , Hu Hongwei , Luo Yuee 
Published: April 2021

Abstract
The 2p photoionization of sodium atoms from the initial states 2p
63p
1/2,3/2 have been investigated, with special emphasis placed on the relaxation and correlation effects. To understand the details of the spectra, a series of ab initio calculations based on the multi-configuration Dirac–Fock method have been performed. Theoretical predictions have been compared with the high-resolution spectra measured using a synchrotron radiation source, and suitable agreement between experiment and theory has enabled the identification of fine-structure spectra. The prominent influence of the relaxation and correlation effects on the photoelectron spectra has been analysed according to the detailed calculations.
An ultra-wideband and wide-angle optically transparent flexible microwave metamaterial absorber
Authors: Zhao Yufan , Li Shuying , Jiang Yuying , Gu Changqing , Liu Liangliang , Li Zhuo 
Published: April 2021

Abstract
In this work, we propose an ultra-wideband and wide-angle optically transparent flexible metamaterial absorber (MMA), consisting of a multilayered structure with a transparent polyvinyl chloride layer and a periodic indium-tin-oxide patch array attached to a polyethylene terephthalate film layer. The absorptivity of the proposed MMA reaches above 90% from 5.61 to 29.17 GHz whether it is flat or even bent with 60º thanks to the flexibility of the materials. Excellent agreement between the measured and simulated results verify our design. The proposed MMA holds great promise in applications for flexible devices that require optical transparency, ultra-wideband and wide angle stealth.
Autonomous shock sensing using bi-stable triboelectric generators and MEMS electrostatic levitation actuators
Authors: Mousavi Mohammad , Alzgool Mohammad , Towfighian Shahrzad 
Published: April 2021

Abstract
This work presents an automatic threshold shock-sensing trigger system that consists of a bi-stable triboelectric transducer and a levitation-based electrostatic mechanism. The bi-stable mechanism is sensitive to mechanical shocks and releases impact energy when the shock is strong enough. A triboelectric generator produces voltage when it receives a mechanical shock. The voltage is proportional to the mechanical shock. When the voltage exceed a certain level, the initially pulled-in microelectromechanical system (MEMS) switch is opened and can disconnect the current in a safety electronic system. The MEMS switch combines two mechanisms of gap-closing (parallel-plate electrodes) with electrostatic levitation (side electrodes) to provide bi-directional motions. The switch is initially closed from a small bias voltage on the gap-closing electrodes. The voltage from the bi-stable generator is connected to the side electrodes. When the shock goes beyond a threshold, the upward force caused by the side electrodes on the switch becomes strong enough to peel off the switch from the closed position. The threshold shock the system can detect is tunable using two control parameters. These two tuning parameters are the axial force on the bi-stable system (clamped-clamped beam) and the bias voltage on the MEMS switch (gap-closing electrodes). The actuation in macro-scale is thus directly connected to a sensor-switch mechanism in micro-scale. This chain makes an autonomous actuation and sensing stand-alone system that has potential application on air bag deployment devices and powerline protection systems. We provide a theoretical frame work of the entire system validated by experimental results.
How Calogero–Moser particles can stick together
Authors: Zabrodin A 
Published: April 2021

Abstract
We show that the configuration in the phase space of the elliptic Calogero–Moser model when particles stick together in pairs is stable under the third Hamiltonian flow of the model. The equations of motion for the pairs coincide with the equations of motion for poles of elliptic solutions to the B-version of the Kadomtsev–Petviashvili equation.
Study of methionine as green corrosion inhibitor for TWIP steel in neutral chloride solution
Authors: Lai Yuming , Gao Ya , Jin Yin , Wen Lei 
Published: April 2021

Abstract
The influence of Methionine (MTI) on corrosion behavior of Twinning induced plastic (TWIP) steel in 3.5wt.% NaCl solutions was investigated using electrochemical techniques, scanning electron microscopy (SEM), white light interferometer (WLI) analyses and Raman spectra. With increasing inhibitor concentration, the corrosion inhibition rate first increased and then decreased, and the maximum inhibitor efficiency was found to be 30 mg l−1 MTI. MTI was acting as a mixed-type inhibitor. The inhibition effect of MTI could also be evaluated by SEM and WLI results, and the trend was the same as that obtained by electrochemistry. At the same time, Raman spectra results showed that MTI was adsorbed on the surface of the steel.
Comparing half-metallic, MOKE, and thermoelectric behavior of the CrTiZ (Z = As, P) half-Heuslers: a DFT study
Authors: Sadeghi M , Zelati A , Boochani A , Arman A , Mirzaei S 
Published: April 2021

Abstract
Structural, half-metallic, magneto-optic, and thermoelectric properties of CrTiZ (Z = As, P) half-Heusleres compounds are investigated based on density functional theory. These compounds have mechanical stability in the ferromagnetic state with a high bulk modulus. They are often half-metallic with a large and integer magnetic moment and are very attractive in spintronics, magneto-optics applications. The magnetic moments of CrTiAs and CrTiP were 2.9865 μ
B and 3.00 μ
B, respectively, which were attributed to their ferromagnetic phase. Additionally, the positive sign of the phonon branches indicates the dynamic stability of these compounds. Applying both GGA and mBJ approximations, CrTiAs and CrTiP compounds exhibited a half-metallic nature by 100% spin polarization. The Kerr angle obtained from magneto-optic results demonstrated a high-intense peak for these compounds in the visible edge with a negative sign. Eventually, a figure of merit with a value above the room temperature was found for both compounds in which the holes are charge carriers.
Reflecting on Your Reflection: Examining the Effect of a Non-Reversing Mirror on Self-Perception
Authors: Frautschi Russell S , Orfahli Lynn M , Zins James E 
Published: April 2021

Abstract

Background
Photographic images can clash markedly with patients’ self-perception. Individuals are more familiar with their mirror image, where their facial asymmetries are reversed. A non-reversing mirror (NRM) allows patients to see their dynamic non-reversed image and familiarize themselves with how they appear in photographs and to others.

Objectives
The aim of this study was to explore the effect that a NRM has on facial self-perception and investigate whether a NRM changes an individual’s goals when considering cosmetic surgery.

Methods
Individuals (n = 30) filled out portions of the FACE-Q questionnaire after inspecting their reflections in a NRM and in a standard mirror for 30 seconds each. After these two inspections had been completed, investigators asked qualitative questions comparing the 2 mirrors. Wilcoxon signed-rank test, Mann-Whitney U test, and Pearson’s chi-squared test were used to analyze the differences.

Results
Participants scored significantly better on the FACE-Q Age Appraisal and Appearance-Related Psychosocial Distress scales when looking in a standard mirror vs a NRM (P = 0.007 and 0.001, respectively). Qualitatively, most reported that their faces seemed less symmetric and less balanced (73% and 53%, respectively) in the NRM. Overall, 83.3% reported seeing a qualitative difference in their appearance, with 30% endorsing that looking in the NRM had changed their facial aesthetic goals.

Conclusions
A NRM can bridge between the familiarity of the patient’s reversed reflection and their less-familiar, non-reversed true image. It may serve as a useful physician-patient communication tool when discussing goals and expectations for facial aesthetic procedures.
Classification of neurological diseases using multi-dimensional CSF analysis
Authors: Gross Catharina C , Schulte-Mecklenbeck Andreas , Madireddy Lohith , Pawlitzki Marc , Strippel Christine , Räuber Saskia , Krämer Julia , Rolfes Leoni , Ruck Tobias , Beuker Carolin , Schmidt-Pogoda Antje , Lohmann Lisa , Schneider-Hohendorf Tilman , Hahn Tim , Schwab Nicholas , Minnerup Jens , Melzer Nico , Klotz Luisa , Meuth Sven G , Meyer zu Hörste Gerd , Baranzini Sergio E , Wiendl Heinz 
Published: April 2021

AbstractAlthough CSF analysis routinely enables the diagnosis of neurological diseases, it is mainly used for the gross distinction between infectious, autoimmune inflammatory, and degenerative disorders of the CNS. To investigate, whether a multi-dimensional cellular blood and CSF characterization can support the diagnosis of clinically similar neurological diseases, we analysed 546 patients with autoimmune neuroinflammatory, degenerative, or vascular conditions in a cross-sectional retrospective study. By combining feature selection with dimensionality reduction and machine learning approaches we identified pan-disease parameters that were altered across all autoimmune neuroinflammatory CNS diseases and differentiated them from other neurological conditions and inter-autoimmunity classifiers that subdifferentiate variants of CNS-directed autoimmunity. Pan-disease as well as diseases-specific changes formed a continuum, reflecting clinical disease evolution. A validation cohort of 231 independent patients confirmed that combining multiple parameters into composite scores can assist the classification of neurological patients. Overall, we showed that the integrated analysis of blood and CSF parameters improves the differential diagnosis of neurological diseases, thereby facilitating early treatment decisions.
A passive and objective measure of recognition memory in Alzheimer’s disease using Fastball memory assessment
Authors: Stothart George , Smith Laura J , Milton Alexander , Coulthard Elizabeth 
Published: April 2021

AbstractEarlier diagnosis of Alzheimer’s disease requires biomarkers sensitive to associated structural and functional changes. While considerable progress has been made in the development of structural biomarkers, functional biomarkers of early cognitive change, unconfounded by effort, practice and level of education, are still needed. We present Fastball, a new EEG method for the passive and objective measurement of recognition memory, that requires no behavioural memory response or comprehension of the task . Younger adults, older adults and Alzheimer’s disease patients (n = 20 per group) completed the Fastball task, lasting just under 3 min. Participants passively viewed rapidly presented images and EEG assessed their automatic ability to differentiate between images based on previous exposure, i.e. old/new. Participants were not instructed to attend to previously seen images and provided no behavioural response. Following the Fastball task, participants completed a two-alternative forced choice (2AFC) task to measure their explicit behavioural recognition of previously seen stimuli. Fastball EEG detected significantly impaired recognition memory in Alzheimer’s disease compared to healthy older adults (P &lt; 0.001, Cohen’s d = 1.52), whereas behavioural recognition was not significantly different between Alzheimer’s disease and healthy older adults. Alzheimer’s disease patients could be discriminated with high accuracy from healthy older adult controls using the Fastball measure of recognition memory (AUC = 0.86, P &lt; 0.001), whereas discrimination performance was poor using behavioural 2AFC accuracy (AUC = 0.63, P = 0.148). There were no significant effects of healthy ageing, with older and younger adult controls performing equivalently in both the Fastball task and behavioural 2AFC task. Early diagnosis of Alzheimer’s disease offers potential for early treatment when quality of life and independence can be retained through disease modification and cognitive enhancement. Fastball provides an alternative way of testing recognition responses that holds promise as a functional marker of disease pathology in stages where behavioural performance deficits are not yet evident. It is passive, non-invasive, quick to administer and uses cheap, scalable EEG technology. Fastball provides a new powerful method for the assessment of cognition in dementia and opens a new door in the development of early diagnosis tools.
Tumour immune landscape of paediatric high-grade gliomas
Authors: Ross James L , Velazquez Vega Jose , Plant Ashley , MacDonald Tobey J , Becher Oren J , Hambardzumyan Dolores 
Published: April 2021

Abstract
Over the past decade, remarkable progress has been made towards elucidating the origin and genomic landscape of childhood high-grade brain tumours. It has become evident that paediatric high-grade gliomas differ from those in adults with respect to multiple defining aspects including: DNA copy number, gene expression profiles, tumour locations within the CNS and genetic alterations such as somatic histone mutations.
Despite these advances, clinical trials for children with gliomas have historically been based on ineffective adult regimens that fail to take into consideration the fundamental biological differences between the two. Additionally, although our knowledge of the intrinsic cellular mechanisms driving tumour progression has considerably expanded, little is known about the dynamic tumour immune microenvironment in paediatric high-grade gliomas.
In this review, we explore the genetic and epigenetic landscape of these gliomas and how this drives the creation of specific tumour subgroups with meaningful survival outcomes. Further, we provide a comprehensive analysis of the paediatric high-grade glioma tumour immune microenvironment and discuss emerging therapeutic efforts aimed at exploiting the immune functions of these tumours.
Nosocomial Outbreak of Coronavirus Disease 2019 by Possible Airborne Transmission Leading to a Superspreading Event
Authors: Cheng Vincent Chi-Chung , Fung Kitty Sau-Chun , Siu Gilman Kit-Hang , Wong Shuk-Ching , Cheng Lily Shui-Kuen , Wong Man-Sing , Lee Lam-Kwong , Chan Wan-Mui , Chau Ka-Yee , Leung Jake Siu-Lun , Chu Allen Wing-Ho , Chan Wai-Shan , Lu Kelvin Keru , Tam Kingsley King-Gee , Ip Jonathan Daniel , Leung Kenneth Siu-Sing , Lung David Christopher , Tse Herman , To Kelvin Kai-Wang , Yuen Kwok-Yung 
Published: April 2021

Abstract

Background
Nosocomial outbreaks with superspreading of coronavirus disease 2019 due to a possible airborne transmission have not been reported.

Methods
Epidemiological analysis, environmental samplings, and whole-genome sequencing (WGS) were performed for a hospital outbreak.

Results
A superspreading event that involved 12 patients and 9 healthcare workers (HCWs) occurred within 9 days in 3 of 6 cubicles at an old-fashioned general ward with no air exhaust built within the cubicles. The environmental contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was significantly higher in air grilles (&gt;2 m from patients’ heads and not within reach) than on high-touch clinical surfaces (36.4%, 8 of 22 vs 3.4%, 1 of 29, P = .003). Six (66.7%) of 9 contaminated air exhaust grilles were located outside patient cubicles. The clinical attack rate of patients was significantly higher than of HCWs (15.4%, 12 of 78 exposed patients vs 4.6%, 9 of 195 exposed HCWs, P = .005). Moreover, the clinical attack rate of ward-based HCWs was significantly higher than of nonward-based HCWs (8.1%, 7 of 68 vs 1.8%, 2 of 109, P = .045). The episodes (mean ± standard deviation) of patient-care duty assignment in the cubicles was significantly higher among infected ward-based HCWs than among noninfected ward-based HCWs (6.0 ± 2.4 vs 3.0 ± 2.9, P = .012) during the outbreak period. The outbreak strains belong to SARS-CoV-2 lineage B.1.36.27 (GISAID clade GH) with the unique S-T470N mutation on WGS.

Conclusions
This nosocomial point source superspreading event due to possible airborne transmission demonstrates the need for stringent SARS-CoV-2 screening at admission to healthcare facilities and better architectural design of ventilation systems to prevent such outbreaks. Portable high-efficiency particulate filters were installed in each cubicle to improve ventilation before resumption of clinical service.
Early impact of the COVID-19 pandemic and social restrictions on ambulance missions
Authors: Laukkanen Lauri , Lahtinen Sanna , Liisanantti Janne , Kaakinen Timo , Ehrola Ari , Raatiniemi Lasse 
Published: April 2021

Abstract

Background
The SARS-CoV-2 coronavirus disease 2019 (COVID-19) has had a major impact on health care services globally. Recent studies report that emergency departments have experienced a significant decline in the number of admitted patients in the early phase of the pandemic. To date, research regarding the influence of COVID-19 on emergency medical services (EMS) is limited. This study investigates a change in the number and characteristics of EMS missions in the early phase of the pandemic.

Methods
All EMS missions in the Northern Ostrobothnia region, Finland (population 295 500) between 1 March to 30 June 2020 were screened and analyzed as the study group. A control group was composed from the EMS calls between the corresponding months in the years 2016–19.

Results
A total of 74 576 EMS missions were screened for the study. Within the first 2 months after the first COVID-19 cases in the study area, the decline in the number of EMS missions was 5.7–13% compared with the control group average. EMS time intervals (emergency call to dispatch, dispatch, en-route, on-scene and hospital handover) prolonged in the COVID-19 period. Dispatches concerning mental health problems increased most in the study period (+1.2%, P &lt; 0.001). Only eleven confirmed COVID-19 infections were encountered by EMS in the study period.

Conclusion
Our findings suggest that the present COVID-19 pandemic and social restrictions lead to changes in the EMS usage. These preliminary findings emphasize the importance of developing new strategies and protocols in response to the oncoming pandemic waves.
Numerical comparison of time-, frequency- and wavelet-domain methods for coda wave interferometry
Authors: Yuan Congcong , Bryan Jared , Denolle Marine 
Published: April 2021

SUMMARYTemporal changes in subsurface properties, such as seismic wave speeds, can be monitored by measuring phase shifts in the coda of two seismic waveforms that share a similar source–receiver path but that are recorded at different times. These nearly identical seismic waveforms are usually obtained either from repeated earthquake waveforms or from repeated ambient noise cross-correlations. The five algorithms that are the most popular to measure phase shifts in the coda waves are the windowed cross correlation (WCC), trace stretching (TS), dynamic time warping (DTW), moving window cross spectrum (MWCS) and wavelet cross spectrum (WCS). The seismic wave speed perturbation is then obtained from the linear regression of phase shifts with their respective lag times under the assumption that the velocity perturbation is homogeneous between (virtual or active) source and receiver. We categorize these methods into the time domain (WCC, TS, DTW), frequency domain (MWCS) and wavelet domain (WCS). This study complements this suite of algorithms with two additional wavelet-domain methods, which we call wavelet transform stretching (WTS) and wavelet transform DTW, wherein we apply traditional stretching and DTW techniques to the wavelet transform. This work aims to verify, validate, and test the accuracy and performance of all methods by performing numerical experiments, in which the elastic wavefields are solved for in various 2-D heterogeneous half-space geometries. Through this work, we validate the assumption of a linear increase in phase shifts with respect to phase lags as a valid argument for fully homogeneous and laterally homogeneous velocity changes. Additionally, we investigate the sensitivity of coda waves at various seismic frequencies to the depth of the velocity perturbation. Overall, we conclude that seismic wavefields generated and recorded at the surface lose sensitivity rapidly with increasing depth of the velocity change for all source–receiver offsets. However, measurements made over a spectrum of seismic frequencies exhibit a pattern such that wavelet methods, and especially WTS, provide useful information to infer the depth of the velocity changes.