bluuebunny/crossref_metadata_2025_split huggingface dataset:
A signature invariant geometric algebra framework for spacetime physics and its applications in relativistic dynamics of a massive particle and gyroscopic precession
Authors: Wu Bofeng 
Published: March 2022

AbstractA signature invariant geometric algebra framework for spacetime physics is formulated. By following the original idea of David Hestenes in the spacetime algebra of signature$$(+,-,-,-)$$(+,-,-,-), the techniques related to relative vector and spacetime split are built up in the spacetime algebra of signature$$(-,+,+,+)$$(-,+,+,+). The even subalgebras of the spacetime algebras of signatures$$(\pm ,\mp ,\mp ,\mp )$$(±,∓,∓,∓)share the same operation rules, so that they could be treated as one algebraic formalism, in which spacetime physics is described in a signature invariant form. Based on the two spacetime algebras and their “common” even subalgebra, rotor techniques on Lorentz transformation and relativistic dynamics of a massive particle in curved spacetime are constructed. A signature invariant treatment of the general Lorentz boost with velocity in an arbitrary direction and the general spatial rotation in an arbitrary plane is presented. For a massive particle, the spacetime splits of the velocity, acceleration, momentum, and force four-vectors with the normalized four-velocity of the fiducial observer, at rest in the coordinate system of the spacetime metric, are given, where the proper time of the fiducial observer is identified, and the contribution of the bivector connection is considered, and with these results, a three-dimensional analogue of Newton’s second law for this particle in curved spacetime is achieved. Finally, as a comprehensive application of the techniques constructed in this paper, a geometric algebra approach to gyroscopic precession is provided, where for a gyroscope moving in the Lense-Thirring spacetime, the precessional angular velocity of its spin is derived in a signature invariant manner.
Continuous cardiac thermometry via simultaneous catheter tracking and undersampled radial golden angle acquisition for radiofrequency ablation monitoring
Authors: Yon Maxime , Delcey Marylène , Bour Pierre , Grissom William , Quesson Bruno , Ozenne Valéry 
Published: March 2022

AbstractThe complexity of the MRI protocol is one of the factors limiting the clinical adoption of MR temperature mapping for real-time monitoring of cardiac ablation procedures and a push-button solution would ease its use. Continuous gradient echo golden angle radial acquisition combined with intra-scan motion correction and undersampled temperature determination could be a robust and more user-friendly alternative than the ultrafast GRE-EPI sequence which suffers from sensitivity to magnetic field susceptibility artifacts and requires ECG-gating. The goal of this proof-of-concept work is to establish the temperature uncertainty as well as the spatial and temporal resolutions achievable in an Agar-gel phantom and in vivo using this method. GRE radial golden angle acquisitions were used to monitor RF ablations in a phantom and in vivo in two sheep hearts with different slice orientations. In each case, 2D rigid motion correction based on catheter micro-coil signal, tracking its motion, was performed and its impact on the temperature imaging was assessed. The temperature uncertainty was determined for three spatial resolutions (1 × 1 × 3 mm3, 2 × 2 × 3 mm3, and 3 × 3 × 3 mm3) and three temporal resolutions (0.48, 0.72, and 0.97 s) with undersampling acceleration factors ranging from 2 to 17. The combination of radial golden angle GRE acquisition, simultaneous catheter tracking, intra-scan 2D motion correction, and undersampled thermometry enabled temperature monitoring in the myocardium in vivo during RF ablations with high temporal (< 1 s) and high spatial resolution. The temperature uncertainty ranged from 0.2 ± 0.1 to 1.8 ± 0.2 °C for the various temporal and spatial resolutions and, on average, remained superior to the uncertainty of an EPI acquisition while still allowing clinical monitoring of the RF ablation process. The proposed method is a robust and promising alternative to EPI acquisition to monitor in vivo RF cardiac ablations. Further studies remain required to improve the temperature uncertainty and establish its clinical applicability.
Combinatorial synthesis of heteroepitaxial, multi-cation, thin-films via pulsed laser deposition coupled with in-situ, chemical and structural characterization
Authors: Moon E. J. , Goyal A. 
Published: March 2022

AbstractCombinatorial synthesis via a continuous composition spread is an excellent route to develop thin-film libraries as it is both time- and cost-efficient. Creating libraries of functional, multicomponent, complex oxide films requires excellent control over the synthesis parameters combined with high-throughput analytical feedback. A reliable, high-throughput, in-situ characterization analysis method is required to meet the crucial need to rapidly screen materials libraries. Here, we report on the combination of two in-situ techniques—(a) Reflection high-energy electron diffraction (RHEED) for heteroepitaxial characterization and a newly developed compositional analysis technique, low-angle x-ray spectroscopy (LAXS), to map the chemical composition profile of combinatorial heteroepitaxial complex oxide films deposited using a continuous composition spread method via pulsed laser deposition. This is accomplished using a unique state-of-the-art combinatorial growth system with a fully synchronized four-axis mechanical substrate stage without shadow masks, alternating acquisition of chemical compositional data using LAXS at various different positions on the $$\sim$$
∼
41 mm $$\times$$
×
41 mm range and sequential deposition of multilayers of SrTiO$$_3$$

3

and $$\hbox {SrTi}_{0.8}\hbox {Ru}_{0.2}\hbox {O}_3$$

SrTi

0.8

Ru

0.2

O
3

on a 2-inch (50.8 mm) $$\hbox {LaAlO}_3$$

LaAlO
3

wafer in a single growth run. Rutherford backscattering spectrometry (RBS) is used to calibrate and validate the compositions determined by LAXS. This study shows the feasibility of combinatorial synthesis of heteroepitaxial, functional complex oxide films at wafer-scale via two essential in-situ characterization tools—RHEED for structural analysis or heteroepitaxy and LAXS for compositional characterization. This is a powerful technique for development of new films with optimized heteroepitaxy and composition.
A multi-source information fusion approach in tunnel collapse risk analysis based on improved Dempster–Shafer evidence theory
Authors: Wu Bo , Qiu Weixing , Huang Wei , Meng Guowang , Huang Jingsong , Xu Shixiang 
Published: March 2022

AbstractThe tunneling collapse is the main engineering hazard in the construction of the drilling-and-blasting method. The accurate assessment of the tunneling collapse risk has become a key issue in tunnel construction. As for assessing the tunneling collapse risk and providing basic risk controlling strategies, this research proposes a novel multi-source information fusion approach that combines Bayesian network (BN), cloud model (CM), support vector machine (SVM), Dempster–Shafer (D–S) evidence theory, and Monte Carlo (MC) simulation technique. Those methods (CM, BN, SVM) are used to analyze multi-source information (i.e. statistical data, physical sensors, and expert judgment provided by humans) respectively and construct basic probability assignments (BPAs) of input factors under different risk states. Then, these BPAs will be merged at the decision level to achieve an overall risk evaluation, using an improved D–S evidence theory. The MC technology is proposed to simulate the uncertainty and randomness of data. The novel approach has been successfully applied in the case of the Jinzhupa tunnel of the Pu-Yan Highway (Fujian, China). The results indicate that the developed new multi-source information fusion method is feasible for (a) Fusing multi-source information effectively from different models with a high-risk assessment accuracy of 98.1%; (b) Performing strong robustness to bias, which can achieve acceptable risk assessment accuracy even under a 20% bias; and (c) Exhibiting a more outstanding risk assessment performance (97.9% accuracy) than the single-information model (78.8% accuracy) under a high bias (20%). Since the proposed reliable risk analysis method can efficiently integrate multi-source information with conflicts, uncertainties, and bias, it provides an in-depth analysis of the tunnel collapse and the most critical risk factors, and then appropriate remedial measures can be taken at an early stage.
Endurance exercise ameliorates Western diet–induced atherosclerosis through modulation of microbiota and its metabolites
Authors: Huang Wen-Ching , Tung Chun-Liang , Yang Yu-Chen S. H. , Lin I-Hsuan , Ng Xin Er , Tung Yu-Tang 
Published: March 2022

AbstractThe World Health Organization determined cardiovascular disease to be the leading cause of death globally; atherosclerosis is the primary cause of the high morbidity and mortality rates. Regular physical activity is an effective strategy for maintaining endothelial health and function to prevent the development of atherosclerosis. Obesity is also a crucial risk factor for atherosclerotic progression in combination with various complications and systemic inflammation. Physiological homeostasis is modulated by the intestinal microbiota, but the mechanisms through which exercise attenuates atherosclerosis through the microbiota have not been elucidated. Therefore, we investigated the effects of endurance exercise on atherosclerosis induced by a Western diet (WD) and apolipoprotein E (ApoE) knockout in terms of microbiota parameters and metabolites. Genetically modified ApoE knockout mice (C57BL/6-Apoeem1Narl/Narl, ApoEKO) and wild-type mice (C57BL6/J) were divided into the following four groups (n = 6), namely, wild-type mice fed a chow diet (WT CD), ApoEKO mice fed a chow diet (ApoE CD), ApoEKO mice fed a WD (ApoE WD), and ApoEKO mice fed a WD and performing endurance exercise (ApoE WD EX), for a 12-week intervention. The WD significantly induced obesity and atherosclerotic syndrome in the ApoE WD group. Severe atherosclerotic lesions and arterial thickness were significantly elevated and accompanied by increases in VCAM-1, MCP-1, TNF-α, and IL-1β for immune cell chemotaxis and inflammation during atherosclerotic pathogenesis in the ApoE WD group. In addition, dysbiosis in the ApoE WD group resulted in the lowest short-chain fatty acid (SCFA) production. Endurance exercise intervention (ApoE WD EX) significantly alleviated atherosclerotic syndrome by reducing obesity, significantly inhibiting VCAM-1, MCP-1, TNF-α, and IL-1β expression, and increasing the production of SCFAs. Modulation of the microbiota associated with inflammation, such as Desulfovibrio, Tyzzerella, and Lachnospiraceae_ge, and increased SCFA production, particularly through an abundance of Rikenellaceae and Dubosiella, were also observed after exercise intervention. Endurance exercise can alleviate WD-induced atherosclerosis through the amelioration of obesity, inflammation, and chemotaxis signaling, which are modulated by the microbiota and derived SCFAs.
Incidence and predictors of left atrial appendage thrombus on transesophageal echocardiography before elective cardioversion
Authors: Wegner Felix K. , Radke Robert , Ellermann Christian , Wolfes Julian , Fischer Alicia J. , Baumgartner Helmut , Eckardt Lars , Diller Gerhard-Paul , Orwat Stefan 
Published: March 2022

AbstractGuidelines recommend transesophageal echocardiography (TEE) before cardioversion in thrombogenic arrhythmias when the requirement of ≥ 3 weeks of anticoagulation is not met. Current data to support this approach, especially with direct oral anticoagulants (DOAC), are scarce. We analyzed consecutive elective pre-cardioversion TEE in a high-volume electrophysiology center for the occurrence of left atrial appendage (LAA) thrombi or reduced LAA flow velocity. Possible predictors were recorded and compared in a multivariate logistic regression analysis. Consecutive pre-cardioversion TEE in 512 patients (148 female, median age 69 years) were included. In all patients, indication for TEE was either intake of anticoagulation < 3 weeks before cardioversion or uncertain adherence to the prescribed anticoagulation regimen. Of the 512 TEE, 19 (3.7%) depicted a LAA thrombus. An additional 41 patients (8.0%) showed either a reduced LAA flow velocity (≤ 20 cm/s), LAA sludge, or both. In a multivariate logistic regression analysis, QRS width on admission 12-lead ECG emerged as a possible predictor of LAA thrombus and reduced LAA flow (p = 0.008). Noteworthy, a high CHA2DS2-VASc score was not associated with an increased risk of reduced LAA emptying velocity and LAA thrombi were even found in patients with a CHA2DS2-VASc score of 0 (n = 1) and 1 (n = 1). The presence of LAA thrombus before an elective cardioversion is a rare event in the age of direct oral anticoagulants. However, LAA thrombi occurred even in supposed low-risk individuals according to the CHA2DS2-VASc score. QRS width may aid in identifying patients at risk of reduced LAA flow velocity.
Squeezed vacuum interaction with an optomechanical cavity containing a quantum well
Authors: Jabri H. , Eleuch H. 
Published: March 2022

AbstractWe investigate a hybrid system consisting of an optomechanical resonator and an optical cavity containing a quantum well. The system is coupled to a squeezed vacuum reservoir. We analyze the effect of the injection of squeezed photons inside the cavity on the intensity spectrum. The system reaches a regime of hybrid resonance where mechanical, excitonic and cavity modes are intermixed. Despite that the optomechanical interaction is the source of the nonlinearity in the system, the optimum squeezing is obtained at the hybrid resonance frequencies. However, when the squeezed vacuum is applied, at these frequencies the minimum squeezing is realized as well as an increase of fluctuations is observed. We show that the squeezed vacuum transforms the coherent states into highly squeezed states of light, and offers a great flexibility to obtain maximal squeezing. Furthermore, a perfect squeezing is predicted.
Reference database of total retinal vessel surface area derived from volume-rendered optical coherence tomography angiography
Authors: Maloca Peter M. , Feu-Basilio Silvia , Schottenhamml Julia , Valmaggia Philippe , Scholl Hendrik P. N. , Rosinés-Fonoll Josep , Marin-Martinez Sara , Inglin Nadja , Reich Michael , Lange Clemens , Egan Catherine , Zweifel Sandrine , Tufail Adnan , Spaide Richard F. , Zarranz-Ventura Javier 
Published: March 2022

AbstractOptical coherence tomography angiography (OCTA) enables three-dimensional, high-resolution, depth-resolved flow to be distinguished from non-vessel tissue signals in the retina. Thus, it enables the quantification of the 3D surface area of the retinal vessel signal. Despite the widespread use of OCTA, no representative spatially rendered reference vessel surface area data are published. In this study, the OCTA vessel surface areas in 203 eyes of 107 healthy participants were measured in the 3D domain. A Generalized Linear Model (GLM) model analysis was performed to investigate the effects of sex, age, spherical equivalent, axial length, and visual acuity on the OCTA vessel surface area. The mean overall vessel surface area was 54.53 mm2 (range from 27.03 to 88.7 mm2). OCTA vessel surface area was slightly negatively correlated with age. However, the GLM model analysis identified axial length as having the strongest effect on OCTA vessel surface area. No significant correlations were found for sex or between left and right eyes. This is the first study to characterize three-dimensional vascular parameters in a population based on OCTA with respect to the vessel surface area.
Replacing quarantine of COVID-19 contacts with periodic testing is also effective in mitigating the risk of transmission
Authors: Foncea Patricio , Mondschein Susana , Olivares Marcelo 
Published: March 2022

AbstractThe quarantine of identified close contacts has been vital to reducing transmission rates and averting secondary infection risk before symptom onset and by asymptomatic cases. The effectiveness of this contact tracing strategy to mitigate transmission is sensitive to the adherence to quarantines, which may be lower for longer quarantine periods or in vaccinated populations (where perceptions of risk are reduced). This study develops a simulation model to evaluate contact tracing strategies based on the sequential testing of identified contacts after exposure as an alternative to quarantines, in which contacts are isolated only after confirmation by a positive test. The analysis considers different number and types of tests (PCR and lateral flow antigen tests (LFA)) to identify the cost-effective testing policies that minimize the expected infecting days post-exposure considering different levels of testing capacity. This analysis suggests that even a limited number of tests can be effective at reducing secondary infection risk: two LFA tests (with optimal timing) avert infectiousness at a level that is comparable to 14-day quarantine with 80–90% adherence, or equivalently, 7–9 day quarantine with full adherence (depending on the sensitivity of the LFA test). Adding a third test (PCR or LFA) reaches the efficiency of a 14-day quarantine with 90–100% adherence. These results are robust to the exposure dates of the contact, test sensitivity of LFA and alternative models of viral load evolution, which suggests that simple testing rules can be effective for improving contact tracing in settings where strict quarantine adherence is difficult to implement.
A retrospective cohort study of 238,000 COVID-19 hospitalizations and deaths in Brazil
Authors: Sobral Marcos Felipe Falcão , Roazzi Antonio , da Penha Sobral Ana Iza Gomes , de Oliveira Brigitte Renata Bezerra , Duarte Gisleia Benini , da Silva Jadson Freire , Nogueira Renata Maria Toscano Barreto Lyra 
Published: March 2022

AbstractThe coronavirus disease (COVID-19) pandemic has overwhelmed health care systems in many countries and bed availability has become a concern. In this context, the present study aimed to analyze the hospitalization and intensive care unit (ICU) times in patients diagnosed with COVID-19. The study covered 55,563 ICU admissions and 238,075 hospitalizations in Brazilian Health System units from February 22, 2020, to June 7, 2021. All the patients had a positive COVID-19 diagnosis. The symptoms analyzed included: fever, dyspnea, low oxygen saturation (SpO2 < 95%), cough, respiratory distress, fatigue, sore throat, diarrhea, vomiting, loss of taste, loss of smell, and abdominal pain. We performed Cox regression in two models (ICU and hospitalization times). Hazard ratios (HRs) and survival curves were calculated by age group. The average stay was 14.4 days for hospitalized patients and 12.4 days for ICU patients. For hospitalized cases, the highest hazard mean values, with a positive correlation, were for symptoms of dyspnea (HR = 1.249; 95% confidence interval [CI], 1.225–1.273) and low oxygen saturation (HR = 1.157; 95% CI 1.137–1.178). In the ICU, the highest hazard mean values were for respiratory discomfort (HR = 1.194; 95% CI 1.161–1.227) and abdominal pain (HR = 1.100; 95% CI 1.047–1.156). Survival decreased by an average of 2.27% per day for hospitalization and 3.27% per day for ICU stay. Survival by age group curves indicated that younger patients were more resistant to prolonged hospital stay than older patients. Hospitalization was also lower in younger patients. The mortality rate was higher in males than females. Symptoms related to the respiratory tract were associated with longer hospital stay. This is the first study carried out with a sample of 238,000 COVID-19 positive participants, covering the main symptoms and evaluating the hospitalization and ICU times.
The temporal dedifferentiation of global brain signal fluctuations during human brain ageing
Authors: Ao Yujia , Kou Juan , Yang Chengxiao , Wang Yifeng , Huang Lihui , Jing Xiujuan , Cui Qian , Cai Xueli , Chen Jing 
Published: March 2022

AbstractThe variation of brain functions as healthy ageing has been discussed widely using resting-state brain imaging. Previous conclusions may be misinterpreted without considering the effects of global signal (GS) on local brain activities. Up to now, the variation of GS with ageing has not been estimated. To fill this gap, we defined the GS as the mean signal of all voxels in the gray matter and systematically investigated correlations between age and indices of GS fluctuations. What’s more, these tests were replicated with data after hemodynamic response function (HRF) de-convolution and data without noise regression as well as head motion data to verify effects of non-neural information on age. The results indicated that GS fluctuations varied as ageing in three ways. First, GS fluctuations were reduced with age. Second, the GS power transferred from lower frequencies to higher frequencies with age. Third, the GS power was more evenly distributed across frequencies in ageing brain. These trends were partly influenced by HRF and physiological noise, indicating that the age effects of GS fluctuations are associated with a variety of physiological activities. These results may indicate the temporal dedifferentiation hypothesis of brain ageing from the global perspective.
Optically-assisted thermophoretic reversible assembly of colloidal particles and E. coli using graphene oxide microstructures
Authors: Joby Jostine Puthenveetil , Das Suman , Pinapati Praveenkumar , Rogez Benoît , Baffou Guillaume , Tiwari Dhermendra K. , Cherukulappurath Sudhir 
Published: March 2022

AbstractOptically-assisted large-scale assembly of nanoparticles have been of recent interest owing to their potential in applications to assemble and manipulate colloidal particles and biological entities. In the recent years, plasmonic heating has been the most popular mechanism to achieve temperature hotspots needed for extended assembly and aggregation. In this work, we present an alternative route to achieving strong thermal gradients that can lead to non-equilibrium transport and assembly of matter. We utilize the excellent photothermal properties of graphene oxide to form a large-scale assembly of silica beads. The formation of the assembly using this scheme is rapid and reversible. Our experiments show that it is possible to aggregate silica beads (average size 385 nm) by illuminating thin graphene oxide microplatelet by a 785 nm laser at low intensities of the order of 50–100 µW/µm2. We further extend the study to trapping and photoablation of E. coli bacteria using graphene oxide. We attribute this aggregation process to optically driven thermophoretic forces. This scheme of large-scale assembly is promising for the study of assembly of matter under non-equilibrium processes, rapid concentration tool for spectroscopic studies such as surface-enhanced Raman scattering and for biological applications.