bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on the characteristics of magneto acoustic emission for mild steel fatigue
Authors: Shen Gongtian , Shen Yongna 
Published: September 2020

Fatigue life of materials or structures can be classified into three stages: fatigue hardening or softening, crack initiation and crack propagation, which includes two stages. Current mature non-destructive testing (NDT) methods can only detect macro or visible cracks in stage II crack propagation. In order to detect and evaluate the fatigue damage occurring before stage II crack propagation quickly and effectively, magneto acoustic emission (MAE) measurement was carried out on laboratory specimens with different numbers of fatigue cycles. With the accumulation of fatigue damage, the RMS of MAE decrease steadily on the whole, making MAE a promising non-destructive method for evaluating fatigue damage. To make MAE applicable in noisy environments, square waveform voltage were selected to excite magnetic fields, and ‘T' type MAE signals with higher amplitude were produced. The variation of MAE with number of fatigue cycles at different excitation intensity indicated that the defects associated with fatigue damage have greater effects on the creation and annihilation of domain walls. The point where the MAE amplitude begins to increase instead of decrease with fatigue can be an indicator for the onset of stage II crack propagation.
This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring'.
Efficient calculation of transient eddy current response from multi-layer cylindrical conductive media
Authors: Theodoulidis Theodoros , Skarlatos Anastassios 
Published: September 2020

The transient response from a transmitter–receiver coil system inside a multi-layer cylindrical conductive configuration is obtained. The particular set-up applies to well logging as well as to eddy current tube testing. In this work, a number of improvements are presented to existing models for an efficient calculation of the induced voltage. These include: domain truncation, novel treatment of arbitrary number of layers in order to avoid computational overflows and efficient time response calculation. The latter is based on a combination of Laplace inversion techniques for short- and long-time transient responses.
This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.
Capacitive imaging for adhesive bonds and quality evaluation
Authors: Huang Xuhui , Hamilton Ciaron , Li Zonglin , Udpa Lalita , Udpa Satish S. , Deng Yiming 
Published: September 2020

Defective adhesive bonds pose significant threats towards structural integrity due to reduced joint strength. The nature of the adhesion of two solids remains poorly understood since the adhesion phenomenon is relevant to so many scientific and technological areas. A concept that has been gaining our attention from the perspective of non-destructive testing is the properties discontinuity of the adhesion. Discontinued properties depend significantly on the quality of the interface that is formed between adhesive and substrate. In this research, discontinued electrical properties at the interface are considered. The simplified model is free from multidisciplinary knowledge of chemistry, fracture mechanics, mechanics of materials, rheology and other subjects. From a practical standpoint, this emphasizes the need to establish a good relationship between electrical properties of adhesive bonds and corresponding measurements. Capacitive imaging (CI) is a technique where the dielectric property of an object is determined from external capacitance measurements. Thus, it is potentially promising since adhesive and substrate differ in terms of dielectric property. At the interface between adhesive and substrate, discontinuity of the dielectric properties causes abrupt changes in electric field spatial distribution and thus alters capacitance measurement by simulating defects in adhesive joints regarding permittivity uncertainties. Further understanding of the cause of degraded adhesion quality can be obtained.
This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.
Resonant frequency tracking mode on eddy current pulsed thermography non-destructive testing
Authors: Miao Ling , Gao Bin , Li Haoran , Tian Guiyun 
Published: September 2020

Eddy current pulsed thermography (ECPT) has been widely used in the field of non-destructive testing due to its safety, non-contact detection, high spatial resolution and intuitive results. Inductive excitation source is an important component of ECPT and provides high-frequency alternating current to drive the excitation coil. However, a resonant frequency distortion phenomenon exists in the excitation source during the detection process, which seriously affects the output power of the excitation source and the sample detection effect. This paper presents a fast resonant frequency tracking loop for full bridge series resonant inverter which is used to search the resonance frequency in real time through direct digital synthesizer (DDS) and all-digital phase-locked loop. Theoretical analysis and simulation are presented to explain the working principle of the loop. Then, an experimental prototype is manufactured which serves as an excitation source for the ECPT experimental system. Compared with traditional excitation sources, the prototype does not need a water-cooled device and the tracking speed can be adjusted by modifying the parameters of DDS. Finally, experiments have been conducted on both artificial slot of 45# steel and natural cracks of rail and stainless steel to investigate the influence of resonant frequency tracking speed on the crack detection. The results revealed that reducing the resonant frequency tracking time can efficiently improve defect detectability and the manufactured prototype showed more application potential.This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.
Terahertz smart dynamic and active functional electromagnetic metasurfaces and their applications
Authors: Yaxin Zhang , Hongxin Zeng , Wei Kou , Lan Wang , Mittleman Daniel M. , Ziqiang Yang 
Published: September 2020

The demand for smart and multi-functional applications in the terahertz (THz) frequency band, such as for communication, imaging, spectroscopy, sensing and THz integrated circuits, motivates the development of novel active, controllable and informational devices for manipulating and controlling THz waves. Metasurfaces are planar artificial structures composed of thousands of unit cells or metallic structures, whose size is either comparable to or smaller than the wavelength of the illuminated wave, which can efficiently interact with the THz wave and exhibit additional degrees of freedom to modulate the THz wave. In the past decades, active metasurfaces have been developed by combining diode arrays, two-dimensional active materials, two-dimensional electron gases, phase transition material films and other such elements, which can overcome the limitations of conventional bulk materials and structures for applications in compact THz multi-functional antennas, diffractive devices, high-speed data transmission and high-resolution imaging. In this paper, we provide a brief overview of the development of dynamic and active functional electromagnetic metasurfaces and their applications in the THz band in recent years. Different kinds of active metasurfaces are cited and introduced. We believe that, in the future, active metasurfaces will be combined with digitalization and coding to yield more intelligent metasurfaces, which can be used to realize smart THz wave beam scanning, automatic target recognition imaging, self-adaptive directional high-speed data transmission network, biological intelligent detection and other such applications.
This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.
Secondary traumatic stress and burnout in healthcare workers during COVID-19 outbreak
Authors: Marzetti F. , Vagheggini G. , Conversano C. , Miccoli M. , Gemignani A. , Ciacchini R. , Panait E. , Orrù G. 
Published: September 2020

AimsTo assess the level of professional burnout and secondary traumatic stress, and to identify potential risk or protective factors among health care workers (HCWs) during the coronavirus disease 2019 (COVID-19) outbreak.Materials and MethodsThis cross-sectional study, based on an online survey, collected demographic data and mental distress outcomes from 184 HCWs from May 1st, 2020, to June,15th, 2020, from 45 different countries. The degree of secondary traumatization was assessed using the Secondary Traumatic Stress Scale (STSS), the degrees of perceived stress and burnout were assessed with Perceived Stress Scale (PSS) and Maslach Burnout Inventory Human Service Survey (MBI-HSS) respectively. Stepwise multiple regression analysis was performed to identify potential risk and protective factors for STS.Results184 HCWs (M=90; Age mean: 46.45; SD:11.02) completed the survey. A considerable proportion of HCWs had symptoms of secondary traumatic stress (41.3%), emotional exhaustion (56.0%), and depersonalization (48.9%). The prevalence of secondary traumatic stress in frontline HCWs was 47.5% while in HCWs working in other units it was 30.3% (p<.023); additionally, the prevalence of the same outcome was 67.1% for the HCWs exposed to patients’ death and 32.9% for those HCWs which were not exposed to the same condition (p<.001). In stepwise multiple regression analysis, perceived stress, emotional exhaustion and exposure to patients’ death remained as significant predictors in the final model for secondary traumatic stress (adjusted R2 = 0.537, p< 0.001).ConclusionsDuring the current COVID-19 pandemic, HCWs facing patients’ physical pain, psychological suffering, and death are more likely to develop secondary traumatization.
AI for radiographic COVID-19 detection selects shortcuts over signal
Authors: DeGrave Alex J. , Janizek Joseph D. , Lee Su-In 
Published: September 2020

AbstractArtificial intelligence (AI) researchers and radiologists have recently reported AI systems that accurately detect COVID-19 in chest radiographs. However, the robustness of these systems remains unclear. Using state-of-the-art techniques in explainable AI, we demonstrate that recent deep learning systems to detect COVID-19 from chest radiographs rely on confounding factors rather than medical pathology, creating an alarming situation in which the systems appear accurate, but fail when tested in new hospitals.
Global incidence of sudden cardiac arrest in young athletes and military members: a systematic review and meta-analysis
Authors: Lear Aaron , Patel Niraj , Mullen Chanda , Simonson Marian , Leone Vince , Koshiaris Constantinos , Nunan David 
Published: September 2020

AbstractObjectivesThe goals of this review are to evaluate the quality of the evidence on epidemiology of SCA/D in athletes and military members; and to synthesize existing data to estimate annual incidence of SCA/D.DesignSystematic review and meta-analysis.Data SourcesMEDLINE, Embase, Cochrane CENTRAL, Web of Science, BIOSIS, Scopus, SPORT discus, PEDro, were searched from inception to date searched between 2/21/19 and 3/1/19, and Clinicaltrials.gov on 7/29/19. All databases were searched without limits on language.Eligibility for selecting studiesStudies which report incidence, or data from which incidence can be calculated, of SCA/D or both in athletes, or military members age 40.Results40 total studies were included. Overall quality of the evidence was judged to be poor. 35 of 40 included studies reported 1,902 events of SCD over 404,268,083 person years and a pooled incidence rate of 1.39events per 100,000 person years (95% CI: 0.80, 2.43) with high heterogeneity (I2=99%). 11 studies reported 219 events of SCA over 13,450,396 person years and a pooled incidence rate of 3.05 events per 100,000 person years (95% CI: 1.42, 6.58) with high heterogeneity (I2=96%).ConclusionThe worldwide incidence of sudden cardiac death and arrest in young otherwise healthy athletes and military personnel is low. Available subgroup analysis showed incidence rates were highest in males; military members, elite athletes; and soccer athletes. Findings are tempered by unexplained heterogeneity and risk of bias in included studies.PROSPERO Registration: CRD42019125560
Sensing of COVID-19 Antibodies in Seconds via Aerosol Jet Printed Three Dimensional Electrodes
Authors: Ali Md. Azahar , Hu Chunshan , Jahan Sanjida , Yuan Bin , Saleh Mohammad Sadeq , Ju Enguo , Gao Shou-Jiang , Panat Rahul 
Published: September 2020

AbstractRapid diagnosis is critical for the treatment and prevention of diseases. In this research, we report sensing of antibodies specific to SARS-CoV-2 virus in seconds via an electrochemical platform consisting of gold micropillar array electrodes decorated with reduced graphene oxide and functionalized with recombinant viral antigens. The array electrodes are fabricated by Aerosol Jet (AJ) nanoparticle 3D printing, where gold nanoparticles (3-5nm) are assembled in 3D space, sintered, and integrated with a microfluidic device. The device is shown to detect antibodies to SARS-CoV-2 spike S1 protein and its receptor-binding-domain (RBD) at concentrations down to 1pM via electrochemical impedance spectroscopy and read by a smartphone-based user interface. In addition, the sensor can be regenerated within a minute by introducing a low-pH chemistry that elutes the antibodies from the antigens, allowing successive testing of multiple antibody samples using the same sensor. The detection time for the two antibodies tested in this work is 11.5 seconds. S1 protein sensing of its antibodies is specific, which cross-reacts neither with other antibodies nor with proteins such as Nucleocapsid antibody and Interleukin-6 protein. The proposed sensing platform is generic and can also be used for the rapid detection of biomarkers for other infectious agents such as Ebola, HIV, and Zika, which will benefit the public health.
Genome sequencing of sewage detects regionally prevalent SARS-CoV-2 variants
Authors: Crits-Christoph Alexander , Kantor Rose S. , Olm Matthew R. , Whitney Oscar N. , Al-Shayeb Basem , Lou Yue C. , Flamholz Avi , Kennedy Lauren C. , Greenwald Hannah , Hinkle Adrian , Hetzel Jonathan , Spitzer Sara , Koble Jeffery , Tan Asako , Hyde Fred , Schroth Gary , Kuersten Scott , Banfield Jillian F. , Nelson Kara L. 
Published: September 2020

AbstractViral genome sequencing has guided our understanding of the spread and extent of genetic diversity of SARS-CoV-2 during the COVID-19 pandemic. SARS-CoV-2 viral genomes are usually sequenced from nasopharyngeal swabs of individual patients to track viral spread. Recently, RT-qPCR of municipal wastewater has been used to quantify the abundance of SARS-CoV-2 in several regions globally. However, metatranscriptomic sequencing of wastewater can be used to profile the viral genetic diversity across infected communities. Here, we sequenced RNA directly from sewage collected by municipal utility districts in the San Francisco Bay Area to generate complete and near-complete SARS-CoV-2 genomes. The major consensus SARS-CoV-2 genotypes detected in the sewage were identical to clinical genomes from the region. Using a pipeline for single nucleotide variant (SNV) calling in a metagenomic context, we characterized minor SARS-CoV-2 alleles in the wastewater and detected viral genotypes which were also found within clinical genomes throughout California. Observed wastewater variants were more similar to local California patient-derived genotypes than they were to those from other regions within the US or globally. Additional variants detected in wastewater have only been identified in genomes from patients sampled outside of CA, indicating that wastewater sequencing can provide evidence for recent introductions of viral lineages before they are detected by local clinical sequencing. These results demonstrate that epidemiological surveillance through wastewater sequencing can aid in tracking exact viral strains in an epidemic context.
A two-site flexible clamp mechanism for RET-GDNF-GFRα1 assembly reveals both conformational adaptation and strict geometric spacing
Authors: Adams Sarah E. , Purkiss Andrew G. , Knowles Phillip P. , Nans Andrea , Briggs David C. , Borg Annabel , Earl Christopher P. , Goodman Kerry M. , Nawrotek Agata , Borg Aaron J. , McIntosh Pauline B. , Houghton Francesca M. , Kjær Svend , McDonald Neil Q. 
Published: September 2020

AbstractRET receptor tyrosine kinase plays vital developmental and neuroprotective roles in metazoans.GDNF family ligands (GFLs) when bound to cognate GFRα co-receptors recognise and activate RET stimulating its cytoplasmic kinase function. The principles for RET ligand-co-receptor recognition are incompletely understood. Here we report a crystal structure of the cadherin-like module (CLD1-4) from zebrafish RET revealing interdomain flexibility between CLD2-CLD3. Comparison with a cryo-EM structure of a ligand-engaged zebrafish RETECD-GDNF-GFRα1 complex indicates conformational changes within a clade-specific CLD3 loop adjacent to co-receptor. Our observations indicate RET is a molecular clamp with a flexible calcium-dependent arm that adapts to different GFRα co-receptors, while its rigid arm recognises a GFL dimer to align both membrane-proximal cysteine-rich domains. We also visualise linear arrays of RETECD-GDNF-GFRα1 suggesting a conserved contact stabilises higher-order species. Our study reveals ligand-co-receptor recognition by RET involves both receptor plasticity and strict spacing of receptor dimers by GFL ligands.HighlightsCrystal structure of zebrafish RET cadherin-like module reveals conformational flexibility at the calcium-dependent CLD2-CLD3 interfaceComparison of X-ray and cryo-EM structures indicate conformational differences between unliganded and liganded RET involving a clade-specific CLD3 loopStrict spatial separation of RETECDC-termini is imposed by each cysteine-rich domain interaction with GFL dimerDifferences in co-receptor engagement and higher-order ligand-bound RET complexes indicate potentially divergent signalling mechanisms
DNA damage and oxidizing conditions activate p53 through differential upstream signaling pathways
Authors: Shi Tao , Polderman Paulien E. , Burgering Boudewijn M.T. , Dansen Tobias B. 
Published: September 2020

AbstractStabilization and activation of the p53 tumour suppressor are triggered in response to various cellular stresses, including DNA damaging agents and elevated Reactive Oxygen Species (ROS) like H2O2. When cells are exposed to exogenously added H2O2, ATR/CHK1 and ATM/CHK2 dependent DNA damage signaling is switched on, suggesting that H2O2induces both single and double strand breaks. These collective observations have resulted in the widely accepted model that oxidizing conditions lead to DNA damage that subsequently mediates a p53-dependent response like cell cycle arrest and apoptosis. However, H2O2induces signaling through stress-activated kinases (SAPK, e.g., JNK and p38MAPK) that can activate p53. Here we dissect to what extent these pathways contribute to functional activation of p53 in response to oxidizing conditions. Collectively, our data suggest that p53 can be activated both by SAPK signaling and the DDR independently of each other, and which of these pathways is activated depends on the type of oxidant used. This implies that it could in principle be possible to modulate redox signaling to stimulate p53 without inducing collateral DNA damage, thereby limiting mutation accumulation in both healthy and tumor tissues.
Phospho-β-catenin expression in primary and metastatic melanomas and in tumor-free visceral tissues
Authors: Pinczewski Joel , Obeng Rebecca , Slingluff Craig L. , Engelhard Victor H. 
Published: September 2020

Abstractβ-catenin (βcat) is an important downstream effector in the Wnt signaling pathway and plays an important role in the development and progression of many cancers including melanoma. βcat expression is regulated by GSK-3β-mediated phosphorylation at positions 33, 37 and 41. In normal cells, phosphorylation at these sites triggers proteasomal degradation, which in turn prevents accumulation of free cytoplasmic βcat. In cancer cells, stabilized β-catenin translocates into the nucleus, where it associates with TCF/Lef proteins to activate transcription of genes that promote tumorigenesis and metastasis. It has been suggested that nuclear phospho-βcat (pβcat) staining may be diagnostically useful in differentiating primary from metastatic melanoma. Also, a pβcat peptide (residues 30-39, p33) is naturally presented by melanoma cells as a T-cell target. We evaluated the expression of pS33-βcat in primary and metastatic melanoma tissues by immunohistochemistry. pS33-βcat was detected in primary and metastatic melanomas and was most commonly cytoplasmic and almost never exclusively nuclear. Interestingly, staining with pS33-βcat and pS33/37/T41-βcat antibodies was most intense in mitotic melanoma cells, consistent with prior studies demonstrating changes in the level of βcat during cell division. We observed no significant differences in pβcat staining location or intensity between primary and metastatic melanomas, suggesting that pβcat may have limited diagnostic or prognostic utility in melanoma. However, the high expression in dividing cells suggests promise as an immunotherapeutic target.
The KOSPI200 Index Option Trading Behavior and Performance of Individual Investors
Authors: Chung Jay M. , Kim Jae Keun 
Published: September 2020

We examine the argument of the Financial Supervisory Service that the behavior of the Individual Investors to buy an out-of-the-money option is excessively speculative. The FSS reported that the individual investors incurred huge losses in the trading of KOSPI200 index options for the years 2002 and 2003. But since the sample period is relatively short, the argument does not seem fully convincing. Using a longer period data from July 1997 to December 2003, we reconfirm the huge losses of the Individual investors and also find that a tendency of individual investors losing money in association with option trading perSisted during the longer period. The individual investors chose out-of-the money options with short time to maturity, that are cheap and thus are expected to make huge profits with very low probabilities. Finally, we tind that out-ot-the money options with short time to maturity turn out to be in general priced higher than what the Korea Stock Exchange model suggests.
The practice of purchasing out-of-the-money options for the reason of cheap prices and huge profit possibilities can be regarded as being excessively speculative. Due to overpricing, the individual investors persistently incurred some losses.