bluuebunny/crossref_metadata_2025 huggingface dataset:
Myocardial Strain Imaging Using Feature Tracking Method of Cardiac MRI: Our Initial Experience of This Novel Parameter as an Additional Diagnostic Tool
Authors: Chudgar Priya D. , Burkule Nitin J. , Kamat Nikhil V. , Rege Gautam M. , Jantre Mansi N.
Published: August 2022

Background Left ventricular ejection fraction (LVEF) is used as quantitative parameter to evaluate myocardial function. However, interobserver variation, limited reproducibility, and dependence on pre-load and after-load reduces its accuracy. The fall in LVEF occurs very late, when myocardial dysfunction is already advanced. Myocardial strain measurements (especially global longitudinal strain) is a new parameter to detect myocardial dysfunction before derangements in LVEF. The aim of this article is to share our experience of this novel diagnostic tool.

Methods Feature tracking method of strain assessment is performed using routine long and short axis cine images of cardiac MRI (CMR). Dedicated post-processing CMR software can perform off-line analysis and provide results in form of color-coded maps, percentage values as well as strain over time curve for each myocardial segments.

Results Global longitudinal strain (GLS) is more sensitive than LVEF and can identify sub-clinical left ventricular (LV) dysfunction in various cardiomyopathies. It is also an important prognostic marker in serial assessment of heart failure patients. Regional differences in strain parameters can provide clues in hypertrophic cardiomyopathy as well as amyloidosis. GLS is recommended as routine measurement in patients undergoing chemotherapy to detect LV dysfunction prior to fall in LVEF. Strain imaging can be applied to guide placement of the LV pacing lead in patients receiving cardiac resynchronization therapy. More clinical data is needed to evaluate its role in ischemic heart disease.

Conclusion Strain imaging can identify LV dysfunction earlier than conventional methods and this opens a new perspective in risk stratification and therapeutic decision-making of various cardiac pathologies.
How should autonomous vehicles drive? Policy, methodological, and social considerations for designing a driver
Authors: Bin-Nun Amitai Y. , Derler Patricia , Mehdipour Noushin , Tebbens Radboud Duintjer
Published: August 2022

Autonomous vehicles (AVs) are being developed, tested, and commercialized around the world. While skilled human drivers can rely on their experience and common sense to navigate complex driving situations that involve trade-offs between competing objectives, AVs are engineered systems, which may handle complex scenarios based on driving principles articulated at the time of system design. This raises the question of what constitutes proper driving behavior in a complex driving scenario. Many jurisdictions point to existing rules of the road as a description of good driving and, by requiring AVs to follow such rules, hope to improve the safety and efficiency of the transportation system. This paper discusses the desirability of a comprehensive definition of AV behavior, reviews subnational, national, and international regulatory developments that seek to define how AVs might drive, and discusses the tensions between safe, lawful, and efficient driving. Locally defined rules of the road can serve as a guide to a comprehensive driving behavior specification. However, translating rules of the road, which are legal documents written in natural language, to formal rules for use by computers deployed on AVs is a challenging task. In particular, the pervasive appeals to judgment that are present in many rules of the road do not easily lend themselves to the precise formalization of conditions and quantification of values that computers use to make decisions. This work also considers the effect that formalizing behavior for adoption by AVs might have on the general driving culture, and especially on the relationship between existing classes of road users. To highlight the challenges associated with formalizing the rules of the road, this work reports on an experiment where two teams independently translated two rules of the road into formal rules to instruct AVs or to verify the correctness of AV behavior. The study results emphasize the desirability of new technical and political structures to mediate a shared understanding of the rules of the road. The harmonization of behavioral expectations has the potential to improve the safety and efficiency of AV deployments, as well as the broader transportation system.
A compact, low jitter, high voltage trigger generator based on fractional-turn ratio saturable pulse transformer and its application
Authors: Geng Jiu-yuan , Yang Jian-hua , Cheng Xin-bing , Chen Rong , Shu Ting
Published: August 2022

In this paper, an all-solid-state high voltage trigger generator is developed, which is aimed at triggering a several gigawatts three-electrode spark gap of an intense electron beam accelerator (IEBA). As one of the most important parts for triggering the IEBA precisely, it is developed based on a fractional-turn ratio saturable pulse transformer and a compact six-stage Marx generator. A pulse of rising time 141 ns and amplitude 79.6 kV is obtained on the 1000 Ω dummy load. The trigger is operated at pulsed repetition frequency over 10 Hz for testing its operational stability. The jitter counted from the initial control signal to the falling edge of the pulse is 0.64 ns. In addition, experiments of three-minute continuous repetitive operations at 10 Hz and higher frequency are carried out. The results show that the trigger generator has high stability even in long-time operations. So far, it successfully applies to the main switch of IEBA with a breakdown voltage of over 500 kV, and a total system jitter of 6.7 ns is acquired.
Patterned diamond anvils prepared via laser writing for electrical transport measurements of thin quantum materials under pressure
Authors: Ku Che-hsuan , Liu Xinyou , Xie Jianyu , Zhang W. , Lam Siu Tung , Chen Y. , Zhou Xuefeng , Zhao Yusheng , Wang Shanmin , Yang Sen , Lai Kwing To , Goh Swee K.
Published: August 2022

Quantum materials exhibit intriguing properties with important scientific values and huge technological potential. Electrical transport measurements under hydrostatic pressure have been influential in unraveling the underlying physics of many quantum materials in bulk form. However, such measurements have not been applied widely to samples in the form of thin flakes, in which new phenomena can emerge, due to the difficulty in attaching fine wires to a thin sample suitable for high-pressure devices. Here, we utilize a home-built direct laser writing system to functionalize a diamond anvil to directly integrate the capability of conducting electrical transport measurements of thin flakes with a pressure cell. With our methodology, the culet of a diamond anvil is equipped with a set of custom-designed conducting tracks. We demonstrate the superiority of these tracks as electrodes for the studies of thin flakes by presenting the measurement of pressure-enhanced superconductivity and quantum oscillations in a flake of MoTe2.
Evidence of surface delocalization in ultrathin films of topological insulator in presence of intersurface hybridization and disorder
Authors: Malasi Megha , Rathod Shivam , Lakhani Archana , Kumar Devendra
Published: August 2022

The study of surface transport in ultrathin films of few quintuple layers thick topological insulators (TIs) and its evolution with disorder is important for TI based device engineering. Here, we demonstrate the absence of Anderson localization in surface states of Bi2Se3 films on varying the disorder from the weak to moderate regime. On increasing the disorder, bulk of topological insulator transforms from diffusive to hopping transport while surface remains in quantum diffusive regime. The weak antilocalization (WAL) of surface states suppresses in thinner films, which could occur due to disorder or inter surface hybridization. Our analysis rules out the role of disorder in WAL suppression and shows that films crossover from decoupled surface states to a single coupled surface bulk channel and finally to hybridized surface states on reducing the film thickness. The dephasing mechanism of surface transport strongly depends on the nature of bulk transport. It is dominated by 2D electron–electron scattering for diffusive bulk transport while it is dominated by direct surface bulk charge puddle coupling and surface to hopping transport coupling for bulk in the variable range hopping regime. The surface to hopping transport coupling weakens with intersurface hybridization.
Unwrapping aortic valve dysfunction through complex network analysis: A biophysics approach
Authors: Vijesh Vijayan , Swapna Mohanachandran Nair Sindhu , Satheesh Kumar Krishan Nair , Sankararaman Sankaranarayana Iyer
Published: August 2022

The development of sensitive and low-cost techniques for identifying valve dysfunction has become inevitable in the context of increasing death due to cardiac diseases. The present work attempts to propose a novel technique for cardiac auscultation based on graph theory. The sixty heart sound signals from normal heart (NMH) and with aortic stenosis (ASH) are subjected to Fast Fourier Transform (FFT) and complex network analyses. The murmur signals, a time-series signal, carry information about the blood flow through the heart, which gets exposed in the graph constructed and its features. The finer details of the murmur signal from the defective aortic valve and the normal aortic valve are reflected as the increased number of frequency components in FFT and as interconnected clusters without uncorrelated nodes in the graph of ASH. The distinction in graph features forms the basis of classification based on machine learning techniques (MLTs). When the unsupervised MLT-principal component analysis gives 86.8% total variance, the supervised MLTs-K nearest neighbor (KNN), support vector machine, and KNN subspace ensemble classifiers give 100%, 95.6%, and 90.9% prediction accuracy, suggesting its potential in remote auscultation in rural health centers.
Design and implementation of sequential excitation module for high fidelity piezoresponse force microscopy
Authors: Song Chunlin , Huang Boyuan , Feng Jun , Li Jiangyu
Published: August 2022

The acquisition of accurate information through a contact resonance mode is critical for mapping weak electromechanical effect reliably by using piezoresponse force microscopy (PFM). However, it is very challenging to track resonance frequency shifting when the contact stiffness from the sample varies significantly. In this work, we have developed a sequential excitation (SE) module to enable high fidelity PFM. A customized discrete frequency sweep signal from an arbitrary waveform generator is used for drive excitation so that resonance frequency tracking is no longer necessary. Furthermore, the AC component of the piezoresponse is sampled by using an oscilloscope instead of using lock-in amplifiers. To accommodate high volume of data acquisition, a fast analysis method is also developed to fit the transfer function of the cantilever efficiently on the fly during scanning. Hardware implementation and data processing are described in detail. The capability of our SE module has been demonstrated on an ordinary PMN-PT film via first and second harmonic PFM, as well as a suspended freestanding MoS2 membrane that is very challenging to probe due to its substantial variation in contact stiffness.
KNN lead-free piezoelectric films grown by sputtering
Authors: Shibata Kenji , Watanabe Kazutoshi , Kuroda Toshiaki , Osada Takenori
Published: August 2022

Potassium sodium niobate [(K,Na)NbO3, KNN] films are promising lead-free piezoelectric materials for microelectromechanical systems (MEMS) devices. We previously developed technologies for forming high-quality KNN films by sputtering, which showed excellent piezoelectric properties comparable to lead zirconate titanate (PZT) films. In the present study, we addressed several challenges with the aim of introducing KNN films into commercialized MEMS devices. First, we optimized the dielectric and piezoelectric properties to realize a suitable performance for actuator and sensor devices. The sensor-type KNN films had a low dielectric constant (248) and a self-poling function, which are greatly beneficial for sensor device performance and the fabrication process. The actuator-type KNN films had a very high e31 value of −13.5 C/m2, which is almost comparable to the top level of PZT films. Next, we found that the DC stress lifetime of KNN films strongly depended on the material used for the adhesion layer of the top electrode. When we used a Pt/RuO2 top electrode, the actuator-type KNN films had a long lifetime (>130 000 s, 300 kV/cm and 200 °C), which is long enough to be used for commercialized MEMS devices. Furthermore, we realized 8-in. KNN wafers with good thickness uniformity across the wafer (±3.5%) by introducing a mass-production-ready sputtering tool: the EB-2500 produced by Canon Anelva. In the near future, these promising results will open the way to replace PZT with KNN in the piezoMEMS industry.
Anomalous properties in the potential energy landscape of a monatomic liquid across the liquid–gas and liquid–liquid phase transitions
Authors: Zhou Yang , Lopez Gustavo E. , Giovambattista Nicolas
Published: August 2022

As a liquid approaches the gas state, the properties of the potential energy landscape (PEL) sampled by the system become anomalous. Specifically, (i) the mechanically stable local minima of the PEL [inherent structures (IS)] can exhibit cavitation above the so-called Sastry volume, vS, before the liquid enters the gas phase. In addition, (ii) the pressure of the liquid at the sampled IS [i.e., the PEL equation of state, PIS(v)] develops a spinodal-like minimum at vS. We perform molecular dynamics simulations of a monatomic water-like liquid and verify that points (i) and (ii) hold at high temperatures. However, at low temperatures, cavitation in the liquid and the corresponding IS occurs simultaneously and a Sastry volume cannot be defined. Remarkably, at intermediate/high temperatures, the IS of the liquid can exhibit crystallization, i.e., the liquid regularly visits the regions of the PEL that belong to the crystal state. The model liquid considered also exhibits a liquid–liquid phase transition (LLPT) between a low-density and a high-density liquid (LDL and HDL). By studying the behavior of PIS(v) during the LLPT, we identify a Sastry volume for both LDL and HDL. The HDL Sastry volume marks the onset above which IS are heterogeneous (composed of LDL and HDL particles), analogous to points (i) and (ii) above. However, the relationship between the LDL Sastry volume and the onset of heterogeneous IS is less evident. We conclude by presenting a thermodynamic argument that can explain the behavior of the PEL equation of state PIS(v) across both the liquid–gas phase transition and LLPT.
Electronic states and transitions of PrO and PrO+ probed by threshold ionization spectroscopy and spin–orbit multiconfiguration perturbation theory
Authors: Zhang Yuchen , Nakamura Taiji , Wu Lu , Cao Wenjin , Schoendorff George , Gordon Mark S. , Yang Dong-Sheng
Published: August 2022

The precise ionization energy of praseodymium oxide (PrO) seeded in supersonic molecular beams is measured with mass-analyzed threshold ionization (MATI) spectroscopy. A total of 33 spin–orbit (SO) states of PrO and 23 SO states of PrO+ are predicted by second-order multiconfigurational quasi-degenerate perturbation (MCQDPT2) theory. Electronic transitions from four low-energy SO levels of the neutral molecule to the ground state of the singly charged cation are identified by combining the MATI spectroscopic measurements with the MCQDPT2 calculations. The precise ionization energy is used to reassess the ionization energies and the reaction enthalpies of the Pr + O → PrO+ + e− chemi-ionization reaction reported in the literature. An empirical formula that uses atomic electronic parameters is proposed to predict the ionization energies of lanthanide monoxides, and the empirical calculations match well with available precise experimental measurements.
Influence of morphological parameters on hemodynamics in internal carotid artery bifurcation aneurysms
Authors: Nagargoje Mahesh S. , Valeti Chanikya , Manjunath N. , Akhade Bhushan , Sudhir B. J. , Patnaik B. S. V. , Kannath Santhosh K.
Published: August 2022

Recent advancements in medical imaging techniques have enabled the accurate identification of unruptured intracranial aneurysms. To facilitate a proper patient management strategy, it is important to develop suitable mathematical models for their rupture prediction. To this end, the development of high-fidelity computational fluid dynamics (CFD) simulations with patient-specific boundary conditions will be useful in providing reliable hemodynamic parameters. In recent review articles, researchers have pointed out that, among several clinical and image-based indicators, morphological parameters, such as aspect ratio (AR) and size ratio (SR) of the aneurysm, correlated consistently with the rupture mechanism. However, it is not clear how these morphological indicators influence the hemodynamics-based CFD predictions. In the present work, the effect of these top-ranked morphological parameters on aneurysm hemodynamics and rupture prediction is investigated. Three patient-specific models have been used for analysis with the patient-specific inlet boundary conditions. We found that with an increase in AR and SR, the maximum value of wall shear stress (WSS) near the aneurysm neck is increased. Oscillatory shear index and relative residence time values are also increased with an increase in AR and SR. Furthermore, it was observed that an aneurysm with a multilobed structure shows complex flow, low WSS, and higher residence time over the secondary lobe. The turbulent kinetic energy and vorticity near the aneurysm neck are also increased with an increase in AR and SR.
Overweight and obesity management in musculo-skeletal primary care: a survey of Australian health practitioners exploring ‘the elephant in the room’
Authors: Stevens John , Orrock Paul , Verco Brent , Egger Garry
Published: August 2022

Background Overweight and obesity has a bi-directional association with the growing burden of musculoskeletal (MSk) dysfunction and pain. It seems inevitable that MSk practitioners will see increasing numbers of patients who are overweight and or obese and require this to be addressed as part of their management. Little evidence exists to describe the engagement of patients and their MSk practitioner in weight management as an adjunct or direct component of their intervention or therapy. Methods A self-administered electronic survey was constructed with 13 items to collect self-reported data from Australian practitioners who have a focus on MSk management. The target group was from a multidisciplinary MSk network of 350 members. Results A total of 204 completed surveys were analysed from respondents working in one of seven MSk- related professions. It was found that 70% of patients/clients seen by respondents were overweight or obese and that <18% of these patients had weight management included as part of their treatment. Conclusions Sixty percent of the respondents in this survey indicated that they do not include weight management as part of their practice despite 70% of their patients/clients being overweight and or obese. With the exception of Medical Practitioners and Exercise Physiologists, in this survey, the other therapists including Chiropractors, Osteopaths, Physiotherapists and Occupational Therapists, indicated that they lacked confidence, knowledge and methods to engage a systematic approach to weight management with their patients/clients.
Lifetime cost of HIV management in Australia: an economic model
Authors: Lim Megumi , Devine Angela , Gray Richard T. , Kwon Jisoo A. , Hutchinson Jolie L. , Ong Jason J.
Published: August 2022

Background Antiretroviral therapy (ART) for HIV has significantly reduced morbidity and mortality, but the drugs can be expensive. This study aimed to estimate the lifetime cost of HIV management from the Australian healthcare perspective. Methods A Markov cohort model, consisting of 21 health states based on CD4 count and line of ART, simulated disease progression over the lifetime of persons living with HIV. We reported costs using 2019 Australian dollars (A$) at a discount rate of 3.5% per annum. One-way sensitivity analysis was used to assess the impact of model inputs, and probabilistic sensitivity analyses were conducted to calculate the 95% confidence intervals for the lifetime cost estimate. Results The average discounted lifetime cost of HIV management was A$282 093 (95% CI: $194 198–421 615). The largest proportion of lifetime cost was due to ART (92%). The lifetime cost was most sensitive to third- and second-line ART costs, followed by the probability of failing third-line therapy for those with a CD4 count of <200 cells/μL. A 20% or 50% reduction in patented ART costs would reduce the lifetime cost to A$243 638 and A$161 400, respectively. Replacing patented ART drugs with currently available generic equivalents reduced the lifetime cost to A$141 345. Conclusion The relatively high lifetime costs for managing HIV mean that ongoing investment will be required to provide care and treatment to people living with HIV, and supports the urgent need to avert new infections. Reducing the price of ARTs (including consideration of generic drugs) would have the most significant impact on lifetime costs.
Conceptual relations
Authors: Nuopponen Anita
Published: August 2022

This chapter gives an overview of concept relations. They can be used to create terminological products, guarantee their quality and make their contents more accessible to the users. They facilitate the analysis, organization, and definition of concepts, and help to establish connections between concepts and terms, to form and evaluate terms, and to identify term equivalents. This chapter first relates conceptual relations to concept formation, and discusses relevant aspects of terminological resources. Then an extensive typology of conceptual relations is compared to typologies with multidisciplinary backgrounds and purposes. Terminology work and terminological resources often use only basic relation types. However, ontologies, automatic term extraction, and advanced terminological knowledge systems benefit from a larger set of relation types.
A “multi-omics” analysis of blood–brain barrier and synaptic dysfunction in APOE4 mice
Authors: Barisano Giuseppe , Kisler Kassandra , Wilkinson Brent , Nikolakopoulou Angeliki Maria , Sagare Abhay P. , Wang Yaoming , Gilliam William , Huuskonen Mikko T. , Hung Shu-Ting , Ichida Justin K. , Gao Fan , Coba Marcelo P. , Zlokovic Berislav V.
Published: August 2022

Apolipoprotein E4 (APOE4), the main susceptibility gene for Alzheimer’s disease, leads to blood–brain barrier (BBB) breakdown in humans and mice. Remarkably, BBB dysfunction predicts cognitive decline and precedes synaptic deficits in APOE4 human carriers. How APOE4 affects BBB and synaptic function at a molecular level, however, remains elusive. Using single-nucleus RNA-sequencing and phosphoproteome and proteome analysis, we show that APOE4 compared with APOE3 leads to an early disruption of the BBB transcriptome in 2–3-mo-old APOE4 knock-in mice, followed by dysregulation in protein signaling networks controlling cell junctions, cytoskeleton, clathrin-mediated transport, and translation in brain endothelium, as well as transcription and RNA splicing suggestive of DNA damage in pericytes. Changes in BBB signaling mechanisms paralleled an early, progressive BBB breakdown and loss of pericytes, which preceded postsynaptic interactome disruption and behavioral deficits that developed 2–5 mo later. Thus, dysregulated signaling mechanisms in endothelium and pericytes in APOE4 mice reflect a molecular signature of a progressive BBB failure preceding changes in synaptic function and behavior.
Pseudospectrum and binary black hole merger transients
Authors: Jaramillo J L
Published: August 2022

The merger phase of binary black hole coalescences is a transient between an initial oscillating regime (inspiral) and a late exponentially damped phase (ringdown). In spite of the non-linear character of Einstein equations, the merger dynamics presents a surprisingly simple behaviour consistent with effective linearity. On the other hand, energy loss through the event horizon and by scattering to infinity renders the system non-conservative. Hence, the infinitesimal generator of the (effective) linear dynamics is a non-selfadjoint operator. Qualitative features of transients in linear dynamics driven by non-selfadjoint (in general, non-normal) operators are captured by the pseudospectrum of the time generator. We propose the pseudospectrum as a unifying framework to thread together the phases of binary black hole coalescences, from the inspiral-merger transition up to the late quasinormal mode ringdown.
Circular stripe domains and cone state vortices in disk-shaped exchange coupled magnetic heterostructures
Authors: Zaiets Oleksandr , Kravchuk Volodymyr P , Pylypovskyi Oleksandr V , Makarov Denys , Sheka Denis D
Published: August 2022

Vertically stacked exchange coupled magnetic heterostructures of cylindrical geometry can host complex noncolinear magnetization patterns. By tuning the interlayer exchange coupling between a layer accommodating magnetic vortex state and an out-of-plane magnetized layer, one can efficiently realize new topological chiral textures such as cone state vortices and circular stripe domains. We study how the number of circular stripes can be controlled by both the interlayer exchange coupling and the sample geometrical parameters. By varying geometrical parameters, a continuous phase transition between the homogeneous state, cone state vortex, circular stripe domains, and the imprinted vortex takes place, which is analysed by full scale micromagnetic simulations. The analytical description provides an intuitive pictures of the magnetization textures in each of these phases. The possibility to realize switching between different states allows for engineering magnetic textures with possible applications in spintronic devices.
Electron-neutral collision cross sections for H2O: I. Complete and consistent set
Authors: Budde Maik , Cunha Dias Tiago , Vialetto Luca , Pinhão Nuno , Guerra Vasco , Silva Tiago
Published: August 2022

This work proposes a complete and consistent set of cross sections (CSs) for electron collisions with water molecules to be published in the IST-Lisbon database on LXCat. The set is validated from the comparison between experimental and computed electron swarm parameters. The former are collected from literature while the latter are calculated using a space-homogeneous two-term Boltzmann solver, assuming isotropic scattering in inelastic collisions. Rotational CSs, based on the Born approximation, are optimised by means of the electron swarm analysis technique. Superelastic rotational and vibrational collisions are accounted for in the calculations and found to be particularly important for low-energy electrons interacting with water molecules. The set can be used with codes assuming space-homogeneous conditions, in particular common two-term Boltzmann solvers, ensuring a good agreement with experiments. Therefore, it constitutes an important tool for fast calculations and modelling of complex plasma chemistries.
A comparison study of InGaN/GaN multiple quantum wells grown on (111) silicon and (0001) sapphire substrates under identical conditions
Authors: Zhu C , Xu C , Feng P , Chen X , de Arriba G M , Bai J , Wang T
Published: August 2022

Due to an increasing demand of developing III-nitride optoelectronics on silicon substrates, it is necessary to compare the growth and optical properties of III-nitride optoelectronics such as InGaN based light emitting diodes (LEDs) on silicon substrates and widely used sapphire substrates. GaN-on-silicon suffers from tensile strain, while GaN-on-sapphire exhibits compressive strain. This paper presents a comparative study of InGaN/GaN multiple quantum wells (MQWs) grown on a silicon substrate and a sapphire substrate under identical conditions. It has been found that GaN strain status has a significant influence on the growth and the optical properties of InGaN/GaN MQWs. Photoluminescence measurements indicate the InGaN/GaN MQWs grown on a silicon substrate exhibit significantly longer wavelength emission than those on a sapphire substrate. Detailed x-ray diffraction measurements including reciprocal space mapping measurements confirm that both indium content and growth rate in the InGaN MQWs on the silicon substrate are enhanced due to the tensile strain of the GaN underneath compared with those on the sapphire substrate. This work also presents an investigation on strain evolution during the InGaN MQWs growth on the two different kinds of substrates. A qualitative study based on in-situ curvature measurements indicates that a strain change on the silicon substrate is much more sensitive to a growth temperature change than that on the sapphire substrate. It is worth highlighting that the results provide useful guidance for optimising growth conditions for III-nitrides optoelectronics on silicon substrates.
Dense velocity, pressure and Eulerian acceleration fields from single-instant scattered velocities through Navier–Stokes-based data assimilation
Authors: Mons V , Marquet O , Leclaire B , Cornic P , Champagnat F
Published: August 2022

In this study, a reconstruction procedure to infer full 3D instantaneous velocity and pressure fields from sparse velocity measurements is proposed, here focusing on the case of scattered data as provided by particle tracking velocimetry (PTV). A key characteristic of the present approach is that it only relies on single-instant velocity measurements, and does not require any time-resolved or acceleration information. It is based on a strong enforcement of the Navier–Stokes equations where the partial time derivative of the velocity field, namely Eulerian acceleration, is considered as a control vector to minimize the discrepancies between the single-instant measurements and the reconstructed flow. Eulerian acceleration is thus a byproduct of the present methodology in addition to the identification of the full velocity and pressure fields. The reconstruction performances of the proposed Navier–Stokes-based data-assimilation approach for single-instant velocity measurements (NS-DA-SIM) are assessed using a numerical dataset for the 3D flow past a cylinder. Comparisons with existing data assimilation methodologies allow to further illustrate the merits of the present approach. The latter is finally applied to the instantaneous reconstruction of an experimental air jet flow from volumetric PTV data, confirming its robustness and high efficacy.
Removing speckle noise from the signals of a laser Doppler vibrometer on moving platforms (LDVom) by ensemble empirical mode decomposition
Authors: Jin Yang , Dollevoet Rolf , Li Zili
Published: August 2022

With increasing requirements for structural stability and durability, effective monitoring strategies for existing and potential damage are necessary. A laser Doppler vibrometer on moving platforms (LDVom) can remotely capture large-scale structural vibrations, but speckle noise, a significant signal issue mainly when one-way continuously scanning from moving platforms, restricts its applications. A novel approach based on ensemble empirical mode decomposition (EEMD) is proposed to eliminate speckle noise. Moving root-mean-square thresholds are used to cut off signal drop-outs. With both numerically simulated and experimentally acquired signals, the proposed EEMD-based approach reveals the true vibrations despite the low initial signal-to-noise ratio. Other methods fail to eliminate the speckle noise. In physical experiments, the despeckled signal energy is concentrated at defect locations in the Hilbert–Huang spectrum. The identified damage locations agree well with the actual damage locations. Therefore, the developed approach demonstrates advantages and robustness of eliminating speckle noise in LDVom signals for damage inspection.
A simple, robust and scalable route to prepare sub-50 nm soft PDMS nanoparticles for intracellular delivery of anticancer drugs
Authors: Maparu Auhin Kumar , Singh Prerana , Rai Beena , Sharma Ashutosh , Sivakumar Sri
Published: August 2022

Soft nanoparticles (NPs) have recently emerged as a promising material for intracellular drug delivery. In this regard, NPs derived from polydimethylsiloxane (PDMS), an FDA approved polymer can be a suitable alternative to conventional soft NPs due to their intrinsic organelle targeting ability. However, the available synthesis methods of PDMS NPs are complicated or require inorganic fillers, forming composite NPs and compromising their native softness. Herein, for the first time, we present a simple, robust and scalable strategy for preparation of virgin sub-50 nm PDMS NPs at room temperature. The NPs are soft in nature, hydrophobic and about 30 nm in size. They are stable in physiological medium for two months and biocompatible. The NPs have been successful in delivering anticancer drug doxorubicin to mitochondria and nucleus of cervical and breast cancer cells with more than four-fold decrease in IC50 value of doxorubicin as compared to its free form. Furthermore, evaluation of cytotoxicity in reactive oxygen species detection, DNA fragmentation, apoptosis-associated gene expression and tumor spheroid growth inhibition demonstrate the PDMS NPs to be an excellent candidate for delivery of anticancer drugs in mitochondria and nucleus of cancer cells.
Scalable approach to fabricate paper-based biomass reduced graphene sensor for the detection of exhaled diabetic breath
Authors: Ajay Rakkesh R , Durgalakshmi D , Balakumar S
Published: August 2022

Herein, we demonstrate a microwave-assisted chemical reduction technique to exfoliate a few layers of graphene from the natural waste material, ‘coconut shell’. The microwave irradiation coconut shell is subjected to structural, morphological and functional groups characterization methods including SEM, Raman, FTIR and XPS spectroscopic analyses. The formation of biomass reduced graphene (BRG) has been confirmed through Raman and FTIR spectroscopic analyzes with the presence of D, G and 2D and other functional spectral bands, respectively. The surface topography of the BRG exhibits two-dimensional mat structures with wrinkle topography, imaged by electron microscopic techniques. The metallic behaviour of the BRG is evaluated by band structure calculation using density functional theory. The synthesized nanostructure has been evaluated for exhaled diabetic breath sensing application by fabricating sensor device on the paper-based substrate by roll-to-roll coating technique. The BRG sensor exhibited enhanced sensing response at a very lower concentration of diabetic biomarker with long term stability and rapid response/recovery time of 1.11 s/41.25 s, respectively. Based on our findings, the microwave-assisted BRG is a potential candidate for fabricating highly scalable, inherently safe, economically viable and excellent sensing performance to detect exhaled diabetic breath at room temperature.
Symmetric domain segmentation in WS2 flakes: correlating spatially resolved photoluminescence, conductance with valley polarization
Authors: Kayal Arijit , Barman Prahalad Kanti , Sarma Prasad V , Shaijumon M M , Kini R N , Mitra J
Published: August 2022

The incidence of intra-flake heterogeneity of spectroscopic and electrical properties in chemical vapour deposited (CVD) WS2 flakes is explored in a multi-physics investigation via spatially resolved spectroscopic maps correlated with electrical, electronic and mechanical properties. The investigation demonstrates that the three-fold symmetric segregation of spectroscopic response, in topographically uniform WS2 flakes are accompanied by commensurate segmentation of electronic properties e.g. local carrier density and the differences in the mechanics of tip-sample interactions, evidenced via scanning probe microscopy phase maps. Overall, the differences are understood to originate from point defects, namely sulfur vacancies within the flake along with a dominant role played by the substrate. While evolution of the multi-physics maps upon sulfur annealing elucidates the role played by sulfur vacancy, substrate-induced effects are investigated by contrasting data from WS2 flake on Si and Au surfaces. Local charge depletion induced by the nature of the sample-substrate junction in case of WS2 on Au is seen to invert the electrical response with comprehensible effects on their spectroscopic properties. Finally, the role of these optoelectronic properties in preserving valley polarization that affects valleytronic applications in WS2 flakes, is investigated via circular polarization discriminated photoluminescence experiments. The study provides a thorough understanding of spatial heterogeneity in optoelectronic properties of WS2 and other transition metal chalcogenides, which are critical for device fabrication and potential applications.
Low-dose CT allows for accurate proton therapy dose calculation and plan optimization
Authors: Elhamiasl Masoud , Salvo Koen , Poels Kenneth , Defraene Gilles , Lambrecht Maarten , Geets Xavier , Sterpin Edmond , Nuyts Johan
Published: August 2022

Objective. Protons offer a more conformal dose delivery compared to photons, yet they are sensitive to anatomical changes over the course of treatment. To minimize range uncertainties due to anatomical variations, a new CT acquisition at every treatment session would be paramount to enable daily dose calculation and subsequent plan adaptation. However, the series of CT scans results in an additional accumulated patient dose. Reducing CT radiation dose and thereby decreasing the potential risk of radiation exposure to patients is desirable, however, lowering the CT dose results in a lower signal-to-noise ratio and therefore in a reduced quality image. We hypothesized that the signal-to-noise ratio provided by conventional CT protocols is higher than needed for proton dose distribution estimation. In this study, we aim to investigate the effect of CT imaging dose reduction on proton therapy dose calculations and plan optimization. Approach. To verify our hypothesis, a CT dose reduction simulation tool has been developed and validated to simulate lower-dose CT scans from an existing standard-dose scan. The simulated lower-dose CTs were then used for proton dose calculation and plan optimization and the results were compared with those of the standard-dose scan. The same strategy was adopted to investigate the effect of CT dose reduction on water equivalent thickness (WET) calculation to quantify CT noise accumulation during integration along the beam. Main results. The similarity between the dose distributions acquired from the low-dose and standard-dose CTs was evaluated by the dose-volume histogram and the 3D Gamma analysis. The results on an anthropomorphic head phantom and three patient cases indicate that CT imaging dose reduction up to 90% does not have a significant effect on proton dose calculation and plan optimization. The relative error was employed to evaluate the similarity between WET maps and was found to be less than 1% after reducing the CT imaging dose by 90%. Significance. The results suggest the possibility of using low-dose CT for proton therapy dose estimation, since the dose distributions acquired from the standard-dose and low-dose CTs are clinically equivalent.
Locating sources of complex quantum networks
Authors: Hongjue Wang , Fangfeng Zhang
Published: August 2022

The source location of quantum network is an important basic research in the direction of quantum networks, which has important scientific and application values in the frontier fields include quantum state tomography, quantum computing, quantum communication, etc. In this paper, we conduct innovative research on quantum network source location algorithm and theory. A matrix vectorization technique is used to establish a linear system evolution model for quantum network system, and then a high-precision and high-efficiency source location algorithm based on compressed sensing is proposed for large-scale complex quantum networks. All the results of numerical simulation on various model and real networks show the effectiveness and feasibility of the proposed algorithm.
Optical-acoustic excitation of broadband terahertz antiferromagnetic spin waves
Authors: Zhang Jinglin , Ge Xu , Yu Shaojie , Yu Lu , Dong Diandian , Song Jianhui , Chen Yangyi , Li JiaPu , Luo Wei , Liang Shiheng , Otani Yoshichika , You Long , Yang Xiaofei , Zhang Yue
Published: August 2022

We propose an optical-acoustic means to excite broadband terahertz antiferromagnetic (AFM) spin wave in a metal/insulator/antiferromagnet heterostructure. The AFM spin wave is excited by an ultrafast strain wave triggered by a femtosecond pulsed laser based on photoacoustic conversion. This spin wave comprises an AFM exchange spin wave and a magnetoelastic spin wave. Their dispersion curves are overlapped in a wide frequency range by manipulating the Dzyaloshinskii–Moriya interaction, which is accompanied by lifting the degeneration of the spin-wave modes with opposite chirality. This optical-acoustic excitation of spin waves exploits the laser-induced ultrafast strain waves and avoids the thermal effect from the laser. It paves a way to develop novel AFM devices that can apply for ultrafast information processing and communication.
Erratum: Capture and decay of electroweak WIMPonium
Authors: Asadi Pouya , Baumgart Matthew , Fitzpatrick Patrick J. , Krupczak Emmett , Slatyer Tracy R.
Published: August 2022

Due to a correction to the relative sign between the two diagrams in figure 1, a new version of the original paper is provided, since this sign propagates through the paper and gives rise to changes in some equations and figures. This affects both capture rate into the boundstates and transition rates between different boundstates. The topline qualitative results of the paper remain unchanged.

The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter generically possesses bound states when the WIMP mass becomes sufficiently large relative to the mass of the electroweak gauge bosons. The presence of these bound states enhances the annihilation rate via resonances in the Sommerfeld enhancement, but they can also be produced directly with the emission of a low-energy photon. In this work we compute the rate for SU(2) triplet dark matter (the wino) to bind into WIMPonium — which is possible via single-photon emission for wino masses above 5 TeV for relative velocity v < O(10-2) — and study the subsequent decays of these bound states. We present results with applications beyond the wino case, e.g. for dark matter inhabiting a nonabelian dark sector; these include analytic capture and transition rates for general dark sectors in the limit of vanishing force carrier mass, efficient numerical routines for calculating positive and negative-energy eigenstates of a Hamiltonian containing interactions with both massive and massless force carriers, and a study of the scaling of bound state formation in the short-range Hulthén potential. In the specific case of the wino, we find that the rate for bound state formation is suppressed relative to direct annihilation, and so provides only a small correction to the overall annihilation rate. The soft photons radiated by the capture process and by bound state transitions could permit measurement of the dark matter's quantum numbers; for wino-like dark matter, such photons are rare, but might be observable by a future ground-based gamma-ray telescope combining large effective area and a low energy threshold.
Lithography-free fabrication and optical characterizations of nanotextured nickel dewetting thin film for broadband absorbers
Authors: Fang Rongpeng , Yu Zhenshan , Lin Yu-Sheng
Published: August 2022

Plasmonic structures based on metamaterials are widely studied and have been extensively researched in various applications. However, the fabrication of regular nanostructures always requires expensive equipment and a strict working environment, lacking the ability for large-scale fabrication. In this study, we propose and demonstrate simple nanotextured nickel (Ni) dewetting thin films on silicon (Si) and quartz substrates by using different thermal annealing temperatures. They achieve a broadband absorption range with near zero reflectivity due to the standing-wave resonances of surface plasmon polariton, and the resonance is relative to the material of the substrate. The topographies of the nanotextured Ni dewetting thin films vary with thermal annealing temperatures at different dewetting stages. The corresponding reflection and absorption resonant wavelengths of the devices are redshifted by increasing the thermal annealing temperatures. The main absorption resonances are at wavelengths of 610 nm, 580 nm, 625 nm, and 660 nm on the Si substrate. While the reflectivity of the sample around the visible range is lower than 40%, it is suitable for broadband absorption for green and yellow spectra. Moreover, the resonant wavelengths are blueshifted by increasing the incident angles. The demonstrated devices are also sensitive to the ambient media. The reflection resonant wavelengths are redshifted by increasing the environmental refraction indexes. The corresponding reflected colors are changed from green to yellow . These devices exhibit a highest sensitivity of 500 nm RIU−1 and can be used for color sensors. This proposed approach has large-scale fabrication capacity and provides promising applications for broadband absorbers, reflective displays, environmental sensors, and other optoelectronic fields.
Structure and function of hard carbon negative electrodes for sodium-ion batteries
Authors: Mittal Uttam , Djuandhi Lisa , Sharma Neeraj , Andersen Henrik L
Published: August 2022

Practical utilisation of renewable energy from intermittent sustainable sources such as solar and wind relies on safe, reliable, cost-effective, and high-capacity energy storage systems to be incorporated into the grid. Among the most promising technologies aimed towards this application are sodium-ion batteries(SIBs). Currently, hard carbon is the leading negative electrode material for SIBs given its relatively good electrochemical performance and low cost. Furthermore, hard carbon can be produced from a diverse range of readily available waste and renewable biomass sources making this an ideal material for the circular economy. In facilitating future developments on the use of hard carbon-based electrode materials for SIBs, this review curates several analytical techniques that have been useful in providing structure-property insight and stresses the need for overall assessment to be based on a combination of complementary techniques. It also emphasises several key challenges in the characterisation of hard carbons and how various in situ and operando techniques can help unravel those challenges by providing us with a better understanding of these systems during operation thereby allowing us to design high-performance hard carbon materials for next-generation batteries.