bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on parameter optimisation of dynamic priority scheduling algorithm based on improved reinforcement learning
Authors: Meng Shanshan , Zhu Qiang , Xia Fei , Lu Jianfeng
Published: May 2020

The dynamic priority scheduling algorithm is one of the real‐time scheduling algorithms in a power system. However, it ignores the impact of the weight of each index when selecting indicators that affect scheduling performance. There is no definite objective function relation between weight parameters and scheduling performance. Hence, the heuristic algorithm is difficult to optimise the weight parameters. Aiming to solve this problem, a dynamic priority scheduling algorithm based on improved reinforcement learning (RL) is proposed for parameter optimisation. By learning from each other, the weighting parameters and the deadline miss rate (DMR), the global optimisation of weighting parameters can be achieved, but the learning efficiency of the conventional RL method is low. According to the task scheduling performance (the DMR) and the task characteristics, this study improves the RL action step and reward function, which accelerates the online learning speed and improves the optimisation ability of the RL algorithm. Experimental results show that the improved RL algorithm not only optimises the weight parameters but reduces the DMR, which reduces the number of iterations of RL. A scheduling algorithm optimised by RL can be better applied to industrial control and power system resource scheduling, which not only improves control efficiency but reduces scheduling costs.
Enhanced Z‐bus method for analytical computation of voltage sensitivities in distribution networks
Authors: Maharjan Salish , Khambadkone Ashwin M. , Peng Jimmy C.‐H.
Published: May 2020

Voltage sensitivity matrices are fundamental for the model‐based control of the distribution networks. Here, an accurate estimation of voltage sensitivity to active/reactive power injections and tap‐position of an on‐load tap changer is essential for network modelling. In literature, voltage sensitivity to tap‐position is computed by assuming its equivalence with voltage sensitivity to voltage magnitude of the slack bus. However, this approach provides an approximate estimation, and it leads to significant error when the external grid has a low strength. Hence, this study proposes an Enhanced Z‐bus method, which comprises of analytical expressions for direct estimation of the voltage sensitivity to tap‐position and active/reactive power injections. Importantly, the enhanced Z‐bus method can accurately compute the voltage sensitivity to tap‐position and active/reactive power injections for any strength of the external grid. The proposed method is tested in a radial (UKGDS), mesh (Case33bw) and reconfigurable (MV Oberrhein) network. Furthermore, it is benchmarked with the perturb‐and‐observe, Jacobian method and the proprietary methods of DigSILENT PowerFactory. Finally, the proposed method is found to be computationally competent with the existing Jacobian and Z‐bus methods.
Global solution method for decentralised multi‐area SCUC and savings allocation based on MILP value functions
Authors: Zheng Xiaodong , Chen Haoyong , Xu Yan , Shen Feifan , Liang Zipeng
Published: May 2020

To address the issue that Lagrangian dual‐function‐based algorithms cannot guarantee convergence and global optimality for decentralised multi‐area security constrained unit commitment (M‐SCUC) problems, a novel decomposition and coordination method using mixed‐integer linear programming (MILP) value functions is proposed. In the proposed solution method, first, each regional system operator sets the tie‐line power injections as variational parameters in its regional SCUC model, and utilises a finite algorithm to generate an MILP value function, which returns the optimal generation cost for any given interchange plan. Then, with the value functions available from all system operators, theoretically, a coordinator is able to devise a globally optimal interchange plan. After the problem is solved, considering that power exchanges may alter the financial position of each area considerably from what it would have been via scheduling independently, the authors then propose a fair savings allocation method using the value functions derived above and the Shapley value in cooperative game theory. Numerical experiments on a two‐area 12‐bus system and a three‐area 457‐bus system were carried out. The validity of the value‐function‐based method was verified for the decentralised M‐SCUC problem. The outcome of savings allocation was compared with that of the locational marginal cost‐based method.
Coarse‐to‐fine 3D road model registration for traffic video augmentation
Authors: Cui Zhichao , Li Yaochen , Zhang Chi , Liu Yuehu , Ren Fuji
Published: May 2020

This study addresses the problem of non‐perspective pose estimation from line correspondences in the traffic scenarios. A coarse‐to‐fine 3D road registration method is proposed for this problem in two stages. Firstly, the iterative closest point algorithm is exploited to estimate the pose coarsely. An objective function is then established to incorporate the feature correspondences for refining the coarse pose. Besides, the framework including road registration is employed for traffic video augmentation. The framework begins with the inputs of traffic videos, road information from Geographic Information Systems and 3D models of traffic elements (e.g. vehicles, pedestrians). Subsequently, 3D road model generation and point‐to‐line correspondence establishment are achieved in the preprossessing stage. After road and viewpoint registration, the 3D graphic engine is employed to simulate the traffic scene with the road, viewpoints and traffic elements. The augmented videos are generated by fusing the original frames and newly projected traffic elements. The authors demonstrate the superiority of the proposed registration method by the comparison to state‐of‐the‐arts in both quantitative and qualitative experiments. In addition, the frames of the augmented videos validate the proposed method in the application.
Subpixel image registration regularised by and norms
Authors: Huang Qirui , Yang Xuan
Published: May 2020

In this study, the authors propose a subpixel image registration framework that detects and matches feature points. Rigid and nonrigid registration models are employed to solve the problem of subpixel image registration problem. A rigid registration model based on the norm is proposed to regularise the rotation coefficients using the indicator function to estimate the rigid transformation parameters. The latter estimation simplified is made easy by the reduction in the rigid transformation from two dimensions to one dimension. Furthermore, a non‐rigid registration model based on the and norms is proposed to estimate the elastic coefficients of the compact support radial basis functions. Due to the linear representation of the transformation function, the rigid and nonrigid subpixel image registration models can be solved efficiently using the fast iterative shrinkage‐thresholding algorithm. Experiments on a demosaicing data set, the ocean of remote sensing data set, a brain data set and the fundus image registration data set show that the proposed rigid and non‐rigid registration models can accurately perform subpixel image registration.
Individual retrieval based on oral cavity point cloud data and correntropy‐based registration algorithm
Authors: Cui Wenting , Liu Jianyi , Du Shaoyi , Liu Yuying , Wan Teng , Han Mengqi , Mou Qingnan , Yang Jing , Guo Yu‐cheng
Published: May 2020

In this study, the authors present a novel individual retrieval method based on oral cavity point cloud data and correntropy‐based registration algorithm. Since the three‐dimensional oral cavity data contains a large amount of noise and outliers, it may lead to a decrease in registration accuracy, which affects the accuracy of retrieval rate. Therefore, the authors introduce the correntropy into the rigid registration algorithm to solve this problem. Then, they filter the matched point cloud data and then use the mean squared error to judge the individual differences of the model data. Finally, the accurate retrieval of the oral cavity data is realised. Experimental results demonstrate the proposed retrieval three‐dimensional model algorithm can be successfully searched under different model data, which can help forensics use the characteristics of biological individuals to accurately search and identify, and improve recognition efficiency.
A point‐based redesign algorithm for designing geometrically complex surfaces. A case study: Miralles's croissant paradox
Authors: Carballal Adrian , Iván Pazos‐Pérez Rafael , Rodriguez‐Fernandez Nereida , Santos Iria , García‐Vidaurrázaga María D. , Rabuñal Juan R.
Published: May 2020

This study explores the use of point clouds for both representation and genetic morphogenesis of complex geometry. The accurate representation of existing objects of complex curved geometry, which are subsequently geometrically modified by evolutionary morphogenetic processes, is analysed. To this end, as a method of representation and generation of complex geometries, a point‐based genetic algorithm and the use of large unstructured point clouds are proposed. A study of convergence and diversity of the implemented algorithm is detailed, as well as a comparison with the Coyote optimisation algorithm in terms of representation error demonstrating its efficiency. Some commonly used three‐dimensional formats in architecture, such as NURBS and polygon meshes, are analysed, and compared against point clouds. This study also includes an evaluation regarding whether the use of point clouds is a more suitable format for realistic representation, rationalisation and genetic morphogenesis.
Production des aciers inoxydables : Histoire et développements. Partie I. Electrométallurgie, production des FeCr
Authors: Saleil Jean , Mantel Marc , Le Coze Jean
Published: May 2020

La production des aciers inoxydables a été l’une des dernières conquêtes techniques de la sidérurgie au 20e siècle. Cet article (en trois parties) s’appuie principalement sur les développements conduits par des sociétés sidérurgiques françaises, pour montrer les étapes techniques successives qui ont permis en moins d’un siècle de passer de productions confidentielles à des productions de grande masse. En matière d’élaboration sont examinées successivement : (Partie I) l’électrométallurgie et la réduction des minerais de chrome ; (Partie II) la fusion électrique, l’affinage sous vide (VOD), l’affinage avec dilution à l’argon (AOD), les filières reposant sur l’affinage de la fonte de hauts fourneaux. La recherche de la haute propreté inclusionnaire est évoquée, notamment avec la refusion ESR. La Partie III traite de la coulée en lingots et en continu et des difficultés liées à la transformation à chaud et à froid de ces nuances, ainsi que des moyens développés pour y faire face.
Reduction of uncertainties in exposure assessment based on environmental monitoring data
Authors: Bleher M. , Gering F. , Stöhlker U. , Karhunen T. , Nalbandyan-Schwarz A. , Woda C. , Mafodda A.
Published: May 2020

Emergency preparedness and response systems for nuclear and radiological emergencies have to deal with decision-making in situations with relevant uncertainties. Consistent and appropriate protective measures must be decided before, during and after emergency situations. CONFIDENCE WP2 research helps to improve this decision-making process in the urgent response and the early response phase of emergency situations with potential major releases to atmosphere. This paper describes methods to reduce uncertainties in dose assessment for the population using data from stationary and mobile environmental monitoring programs. A special focus is given to identification of the measurement uncertainties of stationary and mobile monitoring systems. Methods to reduce these uncertainties and procedures to optimise mobile monitoring strategies are discussed. A first contribution towards assessing the quality of dose-rate measurements performed by the general population is made. In addition, the paper introduces approaches for advanced dose assessment tools using monitoring data and concepts for identifying critically exposed groups.
Wie Hund und Katz – Wenn das Konstitutionsmittel zum Rettungsschirm wird …
Authors: Bitsch Manuela
Published: May 2020

Konstitutionsmittel modulieren die Reaktionsweisen auf innere und äußere Belastungen, sie setzen quasi die Reizschwelle herauf. Im Falle von Hund und Katze, die ein ernsthaftes Problem im Umgang miteinander haben, kann dadurch ein Zusammenleben in gegenseitiger Toleranz erreicht werden. Im hier vorgestellten Fall brauchten beide Tiere, obwohl diese nicht unterschiedlicher sein könnten, das gleiche Mittel. Dies ist unter anderem dadurch zu erklären, dass es bei vielen Konstitutionsmitteln große Unterschiede zwischen dem jungen und dem alten Typus gibt. Ein Grundmuster ist vorhanden, doch man übersieht es nur allzu leicht.
Großflächige Verbrennung – Wenn ein komplexer Akutfall ganzheitlich behandelt wird …
Authors: Bitsch Manuela
Published: May 2020

Trotz großflächiger Verbrennung und lokaler Wundinfektion durch Methicillin resistente Staphylokokken (MRSA) zeigte Maja einen überraschend guten Heilungsverlauf bei weitestgehend ungestörtem Allgemeinbefinden. Dies wäre ohne den ganzheitlichen Behandlungsansatz, der schul- und alternativmedizinische Methoden beinhaltete, so nicht möglich gewesen. Im Hinblick auf die Wahl der Homöopathika hat sich gezeigt, dass bei komplexen oder schwerwiegenden Erkrankungen ein Mittelwechsel erforderlich sein kann. Die vorherige Behandlung mit einem Konstitutionsmittel erwies sich für Maja als glücklicher Zufall, da ihr Körper sich dadurch deutlich besser mit dem schweren Trauma auseinandersetzen konnte.
Aus der Praxis – für die Praxis: Qualifikationsmix im Studium Psychiatrische Pflege
Authors: Zielke-Nadkarni Andrea
Published: May 2020

Haben Sie schon mal darüber nachgedacht, sich an der Hochschule weiter zu qualifizieren – hatten dann aber keinen Mut, diesen Schritt zu wagen? Dann ist vielleicht der neue Studiengang „Psychiatrische Pflege/Psychische Gesundheit“ am Fachbereich Gesundheit der Fachhochschule Münster genau das Richtige für Sie. Die Besonderheit hier: Der Qualifikationsmix knüpft direkt an Ihre praktische pflegerische Tätigkeit an und durch die enge Verzahnung von Theorie und Praxis entwickeln Sie Ihre fachlichen Kompetenzen weiter.
Nutzbarkeit digitaler Anamnesehilfen für nicht-deutschsprachige Patienten in der allgemeinärztlichen Sprechstunde
Authors: Kleinert Evelyn , Müller Frank , Kruse Stefan , Furaijat Ghefar , Simmenroth Anne
Published: May 2020

Ziel der Studie Im Forschungsprojekt DICTUM-Friedland wurde eine Anamnese-App, welche die häufigsten allgemeinmedizinischen Beschwerden und Risikofaktoren in 13 Sprachen bzw. Dialekten erfragt und anschließend eine deutsche Zusammenfassung (Synopse) erzeugt, in einer Erstaufnahmeeinrichtung für Geflüchtete implementiert. Anschließend wurde die Bedienbarkeit und die inhaltliche Plausibilität der App evaluiert um sie für einen Einsatz in einem breiteren allgemeinmedizinischen Setting zu testen und zu optimieren.

Methodik Von Mai bis Dezember 2018 wurde die App im Wartezimmer der allgemeinmedizinischen Sprechstunde im Grenzdurchgangslager Friedland in Südniedersachsen getestet. Die Bedienbarkeit der App wurde mithilfe eines kurzen digitalen Fragebogens direkt nach der App-Nutzung erfragt. Soziodemografische Daten wurden z.T. mit demselben Fragebogen erfasst und z.T. aus Patientenunterlagen extrahiert. Die Plausibilität wurde anhand der Übereinstimmung von eingegebenen Beschwerden (ICPC-2) und ärztlicher Diagnose (ICD-10) überprüft.

Ergebnisse Insgesamt wurde die App 353 Mal verwendet, wovon 283 Anamneseerhebungen abgeschlossen wurden. Die Eingabe der Beschwerden dauerte im Median 10:27 Minuten. Die Verwendung der Audio-Ausgabe (60% der Nutzenden) beeinflusste die Nutzungsdauer nicht. Größtenteils wurde die App als gut bedienbar (76%) eingeschätzt und 65% der Nutzenden gaben an, ihre wesentlichen Beschwerden eingeben zu können. Beide Einschätzungen waren unabhängig vom Alter und vom Geschlecht der Nutzenden, jedoch hatte der Bildungsstand einen leicht positiven Einfluss auf die Bedienbarkeit. Der Plausibilitätstest ergab, dass 51% (N=144) der Synopsen vollständig und 28% (N=79) der Synopsen teilweise mit den ärztlichen Diagnosen übereinstimmten.

Schlussfolgerung Die systematisierte Abfrage häufiger allgemeinmedizinischer Beschwerden ermöglicht eine genauere Anamneseerhebung bei Erkrankten, mit denen ein übliches Anamnesegespräch aufgrund sprachlicher Barrieren nicht möglich ist. Somit dient sie als Unterstützung für das ärztliche Anamnesegespräch. Die App ist leicht bedienbar und im Vergleich zu online verfügbaren maschinellen Übersetzungen nicht anfällig für Übersetzungsfehler.
Digital begleitet – Tele-Coaching
Authors: Kittlick Cornelia
Published: May 2020

Gerade bei chronischen Erkrankungen kann eine engmaschige telemedizinische Betreuung der Patienten entscheidend für den Therapieerfolg und deren subjektiv empfundene Lebensqualität sein. Cornelia Kittlick von Thieme TeleCare gibt einen Einblick in das digitale Angebot ProPerspektive.online für Menschen mit psychischen Belastungen.
Mitarbeiterinfektionsschutz in Zeiten der Coronavirus-Pandemie: Die
akute Implementierung von telemedizinischen Mitarbeiterkonferenzen „von
Null auf Hundert“
Authors: König Tatjana Tamara , Lenz Anna-Franziska , Goedeke Jan , Muensterer Oliver J.
Published: May 2020

Ziel der Studie Die geltenden verschärften Hygieneempfehlungen
des Robert-Koch-Instituts zur Eindämmung der Ausbreitung des Coronavirus
mit Versammlungsverbot und Mindestabstand sind im innerklinischen Alltag nicht
umsetzbar. Zur Minimierung von persönlichen Kontakten wurden die
internen Arztkonferenzen auf ein Videokonferenzformat
umgestellt.

Methodik Innerhalb 24 Stunden wurde unter Anschaffung von
Standard-Webcams, Auswahl eines lizenzierten Videoanbieters und Ausnutzen der
bereits vorhandenen technischen Geräte die allgemeine Hygienerichtlinie
für unsere Mitarbeiter umgesetzt. Häufige Fehlerquellen im
Rahmen der Videokonferenz wurden protokolliert und technische Lösungen
erarbeitet.

Ergebnisse Die Videokonferenz ermöglichte die
adäquate Patientenversorgung und Aufrechterhaltung der gewohnten
organisatorischen Abläufe. In 4 Wochen konnten 956 persönliche
Kontakte vermieden werden. Die meisten Fehler traten im Rahmen der ersten
Teilnahme einer Person oder Erstanmeldung eines Gerätes auf. Die
häufigsten Fehler betrafen die Tonqualität und konnten umgangen
werden, indem nur an der Diskussion beteiligte Teilnehmer ihr Mikrofon
für die Sprechdauer
aktivierten.

Schlussfolgerung Mitarbeiterkonferenzen im Videoformat
können mit geringem personellem und technischem Aufwand etabliert
werden, um der Ausbreitung des Coronavirus unter medizinischem Personal
entgegenzuwirken.
Eyelid Complications Associated with Surgery for Periocular Cutaneous Malignancies
Authors: Carniciu Anaïs L. , Jovanovic Nina , Kahana Alon
Published: May 2020

Periocular skin is highly prone to malignancies, especially basal cell and squamous cell carcinomas. Because of the complex anatomy and eye-protecting functions of the periocular tissues, treatment of these cancers requires special considerations. Mohs micrographic surgery is usually the treatment of choice, whenever possible, in order to enhance margin control while limiting collateral damage to nearby normal structures. Cancer excision, whether by Mohs or other techniques, will leave a complex defect that requires careful anatomical and functional reconstruction. This study presents some of the challenges of treating periocular skin cancer and associated reconstructive surgery and provides an intellectual framework for addressing these challenges. The key topics are adherence to anatomical landmarks and aesthetic units, proper distribution of tension, and matching the correct reconstructive approach, that is, type of flap or graft, to the defect at hand. This review is not meant to be exhaustive, but it will provide both basic and advanced considerations.
Thermomechanical response of thickly tamped targets and diamond anvil cells under pulsed hard x-ray irradiation
Authors: Meza-Galvez J. , Gomez-Perez N. , Marshall A. S. , Coleman A. L. , Appel K. , Liermann H. P. , McMahon M. I. , Konôpková Z. , McWilliams R. S.
Published: May 2020

In the laboratory study of extreme conditions of temperature and density, the exposure of matter to high intensity radiation sources has been of central importance. Here, we interrogate the performance of multi-layered targets in experiments involving high intensity, hard x-ray irradiation, motivated by the advent of extremely high brightness hard x-ray sources, such as free electron lasers and 4th-generation synchrotron facilities. Intense hard x-ray beams can deliver significant energy in targets having thick x-ray transparent layers (tampers) around samples of interest for the study of novel states of matter and materials’ dynamics. Heated-state lifetimes in such targets can approach the microsecond level, regardless of radiation pulse duration, enabling the exploration of conditions of local thermal and thermodynamic equilibrium at extreme temperature in solid density matter. The thermal and mechanical responses of such thick layered targets following x-ray heating, including hydrodynamic relaxation and heat flow on picosecond to millisecond timescales, are modeled using radiation hydrocode simulation, finite element analysis, and thermodynamic calculations. Assessing the potential for target survival over one or more exposures and resistance to damage arising from heating and resulting mechanical stresses, this study doubles as an investigation into the performance of diamond anvil high pressure cells under high x-ray fluences. Long used in conjunction with synchrotron x-ray radiation and high power optical lasers, the strong confinement afforded by such cells suggests novel applications at emerging high intensity x-ray facilities and new routes to studying thermodynamic equilibrium states of warm, very dense matter.
Retrospective clinical trial experimentally validates glioblastoma genome-wide pattern of DNA copy-number alterations predictor of survival
Authors: Ponnapalli Sri Priya , Bradley Matthew W. , Devine Karen , Bowen Jay , Coppens Sara E. , Leraas Kristen M. , Milash Brett A. , Li Fuqiang , Luo Huijuan , Qiu Shi , Wu Kui , Yang Huanming , Wittwer Carl T. , Palmer Cheryl A. , Jensen Randy L. , Gastier-Foster Julie M. , Hanson Heidi A. , Barnholtz-Sloan Jill S. , Alter Orly
Published: May 2020

Modeling of genomic profiles from the Cancer Genome Atlas (TCGA) by using recently developed mathematical frameworks has associated a genome-wide pattern of DNA copy-number alterations with a shorter, roughly one-year, median survival time in glioblastoma (GBM) patients. Here, to experimentally test this relationship, we whole-genome sequenced DNA from tumor samples of patients. We show that the patients represent the U.S. adult GBM population in terms of most normal and disease phenotypes. Intratumor heterogeneity affects ≈11% and profiling technology and reference human genome specifics affect <1% of the classifications of the tumors by the pattern, where experimental batch effects normally reduce the reproducibility, i.e., precision, of classifications based upon between one to a few hundred genomic loci by >30%. With a 2.25-year Kaplan–Meier median survival difference, a 3.5 univariate Cox hazard ratio, and a 0.78 concordance index, i.e., accuracy, the pattern predicts survival better than and independent of age at diagnosis, which has been the best indicator since 1950. The prognostic classification by the pattern may, therefore, help to manage GBM pseudoprogression. The diagnostic classification may help drugs progress to regulatory approval. The therapeutic predictions, of previously unrecognized targets that are correlated with survival, may lead to new drugs. Other methods missed this relationship in the roughly 3B-nucleotide genomes of the small, order of magnitude of 100, patient cohorts, e.g., from TCGA. Previous attempts to associate GBM genotypes with patient phenotypes were unsuccessful. This is a proof of principle that the frameworks are uniquely suitable for discovering clinically actionable genotype–phenotype relationships.
Control of binary states of ferroic orders in bi-domain BiFeO3 nanoislands
Authors: Alyabyeva N. , Ouvrard A. , Bavencoffe M. , Lindfors-Vrejoiu I. , Kolomiytsev A. , Solodovnik M. , Ageev O. , McGrouther D.
Published: May 2020

Understanding switching mechanisms in multiferroics such as BiFeO3 (BFO) is an important challenge to control ferroic orders (ferroelectric or ferroelastic) as it could lead to the design of non-volatile memories based on magnetoelectric coupling. Here, we demonstrate an alternative way to control the binary states of ferroic orders by locally applying pressure and electric field in ferroelectric bi-domains confined in single BFO nanoislands. The study of the electronic transport properties and domain orientations using atomic force microscopy (AFM) based techniques enabled us to determine the electric and mechanical parameters at which ferroelectric and ferroelastic resistive switching can be observed. Nanoislands exhibited binary high and low resistance states without scaling effect, with high performance switching characteristics. Positive-forward rectifying behavior at high tip force was interpreted by the formation of a subsurface non-conductive interface due to the strain gradient. Ferroelastic switching at the surface was associated with a symmetry-breaking induced by electromechanical coupling between the AFM tip and the BFO thin film. It led to out-of-plane polarization pinning that allows performing only in-plane switching accompanied by nucleation and propagation of a conductive domain wall. The control of ferroic binary states by the electric field and pressure may pave the way for multilevel data storage devices.
Coupled oscillations of VO2-based layered structures: Experiment and simulation approach
Authors: Tobe Ryuta , Mian Md. Suruz , Okimura Kunio
Published: May 2020

Vanadium dioxide (VO2) film was deposited on a conductive indium-tin-oxide (ITO) layer on glass by inductively-coupled-plasma (ICP)-assisted rf reactive sputtering. The VO2 film showed insulator–metal transition (IMT) with three orders of magnitude resistance change at around 78 °C. Two VO2-based layered structures (LSs) are capacitively coupled resulting in emerging self-sustaining oscillations up to 1 MHz by adjusting the series resistance and the supplied voltage. Furthermore, we observe weak, chaotic, and strong coupling modes. Our experimental results are corroborated by theoretical circuit simulations that successfully reconstruct the coupled-oscillation phenomena and clarify the mechanisms responsible for the realized synchronization modes. These results will contribute to the physics and engineering application of VO2-based coupled oscillators.
A built-up-type deformable phantom for target motion control to mimic human lung respiration
Authors: Lee Hyuk Jin , Lee Hae Jin , Lee Jeong Su , Kang Yung-Nam , Koo Ja Choon
Published: May 2020

Existing human lung-mimicking requirements in various radiology application fields have led to the development of many different phantoms. However, most are static apparatus designed for equipment calibration. Although there are a few dynamic phantoms that generate predefined motions, they have complicated mechanisms that hamper even simple modifications for various lung illness simulations. As a result, existing dynamic phantoms in which a target can be embedded normally generate rectilinear target motions with limited displacement. Nevertheless, volume changes in the human lungs during normal respiration are significant, and targets inside the lungs move along various random paths depending on their location, stiffness, and the properties of the surrounding tissues. In the present work, a novel phantom design is introduced and tested. The phantom mimics the human lung motion and its deformation is initiated by a diaphragm movement. The phantom provides a fairly large deformation and the capability to adjust target motion paths. The presented device has a simple mechanism that can be easily modified to generate various pulmonary diseases. To produce a large deformation by diaphragm compressive motion, polyurethane cubic blocks constitute the deformable part of the lung phantom and a tumor made with silicone is inserted in the structure. The assembled lung part is housed within an acrylic case that is filled with water. The phantom system consists of acrylic, plastic, and low-density polyurethane to minimize artifacts when it undergoes computed tomography (CT) scans. The lung part is organized with various density polyurethane blocks, making it possible to produce nonlinear motion paths of the tumor. The lung part is deformed by a silicon film that is driven by external hydraulic pressure. A finite element method simulation and two-dimensional target motion tests were performed to verify phantom performance. The functionality of the proposed phantom system was confirmed in a series of CT images.
Mode-specific vibrational predissociation dynamics of (HCl)2 via the free and bound HCl stretch overtones
Authors: Kapnas Kara M. , Murray Craig
Published: May 2020

Velocity-map ion imaging has been used to study the vibrational predissociation dynamics of the HCl dimer following infrared (IR) excitation in the HCl stretch overtone region near 1.77 Å. HCl monomer predissociation products were detected state-selectively using 2 + 1 resonance-enhanced multiphoton ionization spectroscopy. The IR action spectrum shows the free HCl stretch (2ν1), the bound HCl stretch (2ν2), and a combination band involving the intermolecular van der Waals stretching mode (2ν2 + ν4). Fragment speed distributions extracted from ion images obtained for a range of HCl(v = 0, 1; J) levels following vibrational excitation on the 2ν1 and 2ν2 bands yield the correlated product pair distributions. All product pairs comprise HCl(v = 1) + HCl(v = 0) and show a strong propensity to minimize the recoil kinetic energy. Highly non-statistical and mode-dependent HCl product rotational distributions are observed, in contrast to that observed following stretch fundamental excitation. Predissociation lifetimes are also mode-dependent: excitation of the free HCl leads to τVP = 13 ± 1 ns, while the bound stretch has a shorter lifetime τVP ≤ 6 ns. The dimer dissociation energy determined from energy conservation (D0 = 397 ± 7 cm–1) is slightly smaller than the previously reported values. The results are discussed in the context of previous observations for (HF)2 and (HCl)2 after excitation of HX stretch fundamentals and models for vibrational predissociation.
A demonstration of donor passivation through direct formation of V-Asi complexes in As-doped Ge1−xSnx
Authors: Khanam Afrina , Vohra Anurag , Slotte Jonatan , Makkonen Ilja , Loo Roger , Pourtois Geoffrey , Vandervorst Wilfried
Published: May 2020

Positron annihilation spectroscopy in the Doppler and coincidence Doppler mode was applied on Ge1−xSnx epitaxial layers, grown by chemical vapor deposition with different total As concentrations (∼1019–1021 cm−3), high active As concentrations (∼1019 cm−3), and similar Sn concentrations (5.9%–6.4%). Positron traps are identified as mono-vacancy complexes. Vacancy-As complexes, V-Asi, formed during the growth were studied to deepen the understanding of the electrical passivation of the Ge1−xSnx:As epilayers. Larger mono-vacancy complexes, V-Asi (i≥2), are formed as the As doping increases. The total As concentration shows a significant impact on the saturation of the number of As atoms (i=4) around the vacancies in the sample epilayers. The presence of V-Asi complexes decreases the dopant activation in the Ge1−xSnx:As epilayers. Furthermore, the presence of Sn failed to hinder the formation of larger V-Asi complexes and thus failed to reduce the donor-deactivation.
Structural, electronic, and magnetic properties of point defects in polyaniline (C3N) and graphene monolayers: A comparative study
Authors: Sevim K. , Sevinçli H.
Published: May 2020

The newly synthesized two-dimensional polyaniline (C3N) is structurally similar to graphene and has interesting electronic, magnetic, optical, and thermal properties. Motivated by the fact that point defects in graphene give rise to interesting features, like magnetization in an all carbon material, we perform density functional theory calculations to investigate vacancy and Stone–Wales type point defects in monolayer C3N. We compare and contrast the structural, electronic, and magnetic properties of these defects with those in graphene. While monovacancies and Stone–Wales defects of C3N result in reconstructions similar to those in graphene, divacancies display dissimilar geometrical features. Different from graphene, all vacancies in C3N have metallic character because of altered stoichiometry; those that have low-coordinated atoms have finite magnetic moments. We further investigate the robustness of the reconstructed structures and the changes in the magnetic moments by applying tensile and compressive biaxial strain. We find that, with the advantage of finite bandgap, point defects in C3N are qualified as good candidates for future spintronics applications.
Efficient reduction for diagnosing Hopf bifurcation in delay differential systems: Applications to cloud-rain models
Authors: Chekroun Mickaël D. , Koren Ilan , Liu Honghu
Published: May 2020

By means of Galerkin–Koornwinder (GK) approximations, an efficient reduction approach to the Stuart–Landau (SL) normal form and center manifold is presented for a broad class of nonlinear systems of delay differential equations that covers the cases of discrete as well as distributed delays. The focus is on the Hopf bifurcation as a consequence of the critical equilibrium’s destabilization resulting from an eigenpair crossing the imaginary axis. The nature of the resulting Hopf bifurcation (super- or subcritical) is then characterized by the inspection of a Lyapunov coefficient easy to determine based on the model’s coefficients and delay parameters. We believe that our approach, which does not rely too much on functional analysis considerations but more on analytic calculations, is suitable to concrete situations arising in physics applications. Thus, using this GK approach to the Lyapunov coefficient and the SL normal form, the occurrence of Hopf bifurcations in the cloud-rain delay models of Koren and Feingold (KF) on one hand and Koren, Tziperman, and Feingold on the other are analyzed. Noteworthy is the existence of the KF model of large regions of the parameter space for which subcritical and supercritical Hopf bifurcations coexist. These regions are determined, in particular, by the intensity of the KF model’s nonlinear effects. “Islands” of supercritical Hopf bifurcations are shown to exist within a subcritical Hopf bifurcation “sea”; these islands being bordered by double-Hopf bifurcations occurring when the linearized dynamics at the critical equilibrium exhibit two pairs of purely imaginary eigenvalues.
Inclined space-coiling metamaterials for highly efficient sound energy transmission at various incident angles
Authors: Jia Xiao , Hong Minghui , Yan Ming
Published: May 2020

In many acoustic components, strong directional response exerts considerable influence on sound wave energy transmission, restricting their widespread applications. Here, we report new designs of an inclined metamaterial channel that enable improved transmission behaviors and broadband performance under variable-angle incident radiation. For the two-dimensional sound wave guide, the tilt angle is tuned to cater for oblique incidences. The inclined metamaterial is modified based on the normal space-coiling sound wave guide with impedance matching layers. At different incident angles, the inclined waveguides are capable of providing proper gradient parameter distributions to match the impedance value of the outside environment and the inner structure. Both experimental and numerical results show that the inclined metamaterial designs improve the broadband transmission efficiency for 2 kHz with specific incident angles. The anomalous refraction behaviors are demonstrated based on the inclined metamaterial units, showing a huge potential for wavefront engineering and acoustic transparency.
The relationship between the three-dimensional structure of porous GaN distributed Bragg reflectors and their birefringence
Authors: Griffin P. H. , Patel K. M. , Zhu T. , Langford R. M. , Kamboj V. S. , Ritchie D. A. , Oliver R. A.
Published: May 2020

Porous GaN distributed Bragg reflectors offer an opportunity to provide the high reflectance, lattice-matched components required for efficient GaN vertical cavity surface emitting lasers. The birefringence of these structures is, therefore, of key interest as it could be used to control the polarization of the emitted light. Here, we present a detailed analysis of the optical birefringence for both laterally etched, patterned structures and self-assembled radial porous structures. We correlate this with the 3D structure of the pores, which we measure through the use of FIB milling and serial block-face SEM imaging. This is a powerful method for imaging the internal nanostructure of the sample and allows the internal pore morphology to be viewed in a reconstruction of any 3D plane. We measure the birefringence of our porous GaN layers as Δn=0.14 with a lower refractive index parallel to the pores (∥) than perpendicular to them (⟂). Using finite element modeling, we accurately reproduce the experimentally observed birefringence trends and find that this can be done by modeling GaN as a perfect dielectric. This indicates that the birefringence arises from the limited width across the pores. This also shows that standard modeling approaches can be used to design porous GaN birefringent devices effectively.
Mass-zero constrained molecular dynamics for electrode charges in simulations of electrochemical systems
Authors: Coretti A. , Scalfi L. , Bacon C. , Rotenberg B. , Vuilleumier R. , Ciccotti G. , Salanne M. , Bonella S.
Published: May 2020

Classical molecular dynamics simulations have recently become a standard tool for the study of electrochemical systems. State-of-the-art approaches represent the electrodes as perfect conductors, modeling their responses to the charge distribution of electrolytes via the so-called fluctuating charge model. These fluctuating charges are additional degrees of freedom that, in a Born–Oppenheimer spirit, adapt instantaneously to changes in the environment to keep each electrode at a constant potential. Here, we show that this model can be treated in the framework of constrained molecular dynamics, leading to a symplectic and time-reversible algorithm for the evolution of all the degrees of freedom of the system. The computational cost and the accuracy of the new method are similar to current alternative implementations of the model. The advantage lies in the accuracy and long term stability guaranteed by the formal properties of the algorithm and in the possibility to systematically introduce additional kinematic conditions of arbitrary number and form. We illustrate the performance of the constrained dynamics approach by enforcing the electroneutrality of the electrodes in a simple capacitor consisting of two graphite electrodes separated by a slab of liquid water.
Influence of acetic acid on the photocatalytic activity of photosensitiser–amphiphilic polymer complexes in the oxidation reaction of tryptophan
Authors: Kardumyan V. V. , Aksenova N. A. , Glagolev N. N. , Timashev P. S. , Solovieva A. B.
Published: May 2020

The effect of acetic acid on the photosensitizing activity of dimegin (DMG), chlorin e6 (Ce6), and their complexes with amphiphilic polymers—Pluronic F-127 and poly-N-vinylpyrrolidone (PVP)—in the model reaction of tryptophan photo-oxidation has been established. It was shown that the photocatalytic activity of photosensitizers (PS), which is characterized by the effective constant of the tryptophan photo-oxidation rate (keff), increases by 1.4 times for DMG, while for Ce6, it decreases by 1.2 times in a weak acidic medium (pH ∼ 4). The influence of acetic acid on the effective constant keff of the tryptophan photo-oxidation rate in the presence of PS–amphiphilic polymer complexes is determined by the nature of the polymer. Thus, the photocatalytic activity of the PS–F127 system decreases at pH ∼ 4.0, and the photocatalytic activity of PS–PVP complexes is insensitive to the presence of acetic acid in the medium. It has been suggested that the observed effects in the PS–F127 system in a weak acidic medium (pH ∼ 4) are associated with the influence of acetic acid on the supramolecular structure of Pluronic F127.
Quantitative photothermal lock-in thermography imaging of curved surfaces of cylindrical solids
Authors: Liu Yu , Sun Ti , Wang Chinhua , Mandelis Andreas
Published: May 2020

We extend the applications of photothermal radiometric diagnostics to continuously curved cylindrical surface solids using lock-in thermography (LIT) imaging, in which both the photothermally induced surface temperature and the angularly dependent infrared radiation emitted by the curved surface are not constant. Specifically, a theoretical photothermal model is established based on the Green Function method from which the thermal-wave field distribution at different azimuthal angles on the curved surface is obtained and characteristics of the thermal-wave field with different material and measurement parameters/schemes are discussed. A laser-infrared photothermal lock-in imaging system for solid cylindrical samples is established, and the thermal diffusivity of AISI 304 cylindrical steel samples is measured directly based on the LIT images combined with empirically obtained infrared radiation angular distributions over the curved surfaces. The experimental results are in excellent agreement with the theory, which provides a fast and non-destructive quantitative tool for thermophysical evaluation of curved surface solids.
Surface recombination velocities for 4H-SiC: Temperature dependence and difference in conductivity type at several crystal faces
Authors: Kato Masashi , Xinchi Zhang , Kohama Kimihiro , Fukaya Shuhei , Ichimura Masaya
Published: May 2020

In bipolar SiC devices, which are promising under ultra-high voltage operation, the carrier lifetime is a highly influential parameter for the device performance. Surface recombination is one of the limiting factors for the carrier lifetime, and quantitative values of the surface recombination velocities are required for the design and development of fabrication processes of the devices. In this study, we observe carrier recombination at various temperatures for the Si- and C-faces of n- and p-type 4H-SiC samples and the a- and m-faces of n-type 4H-SiC samples with a treatment of chemical mechanical polishing or reactive ion etching by using the microwave photoconductivity decay method. From the experimental results, we estimate surface recombination velocities and bulk carrier lifetimes of the samples by using an analytical model. As a result, we found the smallest surface recombination velocity of 150 cm/s for the chemical mechanical polished surface of the Si-face of the n-type samples at room temperature. Surface recombination velocities increased with temperature for the chemical mechanical polished surfaces. The surfaces treated with reactive ion etching showed relatively large surface recombination velocities with weak temperature dependence. Based on these results, we discuss the origins of the recombination centers at surfaces of 4H-SiC.
Effects of the interfacial defects in Au/ TiO2 on plasmon-induced water oxidation
Authors: Li Hao , Wang Shengyang , Hong Feng , Gao Yuying , Zeng Bin , Haider Rida Shahzadi , Fan Fengtao , Huang Jiahui , Li Can
Published: May 2020

In the plasmonic metal–semiconductor systems, the interfacial structure is vital for both charge separation and photocatalytic reaction. However, the role of interfacial defects, a ubiquitous phenomenon in the metal–semiconductor heterostructure, is not well understood, especially for the hot hole-involved water oxidation reaction. Herein, we studied the effect of interfacial defects, derived from oxygen vacancies, on plasmonic photocatalytic water oxidation. In addition, we found that the plasmon-induced water oxidation activity decreased with the increase in the oxygen vacancies present at the interface, and the activity of Au/TiO2 can be restored after eliminating the defects via a post-oxidation treatment. It is elucidated that a defect state appeared below the conduction band of TiO2 as a result of interfacial defects, which acts as the electron traps and backward transfer channel for electrons to combine with the holes left at the interface. The charge recombination at defect sites leads to the shorter lifetime of hot holes, which is harmful for the kinetics-sluggish water oxidation. This work emphasizes the significance of the interface structure for the plasmon-based photocatalytic process.
Molecular basis of COVID-19 pathogenesis
Authors: Novikov Fedor N. , Stroylov Viktor S. , Svitanko Igor V. , Nebolsin Vladimir E.
Published: May 2020

The review summarizes the publications, available at the time it was written, addressing the chemical and biological processes that occur in the human body upon exposure to coronaviruses, in particular SARS-CoV-2. The mechanisms of viral particle entry into the cell, viral replication and impact on the immune system and on oxygen transport system are considered. The causes behind complications of the viral infection, such as vasculitis, thrombosis, cytokine storm and lung fibrosis, are discussed. The latest research in the field of small molecule medications to counteract the virus is surveyed. Molecular targets and possible vectors to exploit them are considered. The review is primarily written for specialists who want to understand the chains of activation, replication, action and inhibition of SARS-CoV-2. Due to the short period of such studies, the data on complexes of small molecule compounds with possible protein targets are not numerous, but they will be useful in the search and synthesis of new potentially effective drugs.

The bibliography includes 144 references.