bluuebunny/crossref_metadata_2025 huggingface dataset:
Micropaleontological study of the Moroccan Mediterranean western coastline foraminifera and their morphological abnormalities
Authors: Afilal Haitam , Trankil Abdellah , Bouzid Saida , Rossi Abdelhamid
Published: August 2021

In order to contribute to the identification of the current faunistic composition of the Moroccan Mediterranean western coastline foraminifera, sediment from 4 stations have been analyzed, along with some abiotic parameters (pH, dissolved oxygen, temperature, and salinity), In order to characterize their populations, different Ecological indices were calculated and compared in the various samples. A total of 3451 individuals belonging to 14 species were recognized (90,26% hyaline, 9,74% porcelaneous, and none agglutinated test was found), all assemblages were dominated mainly by Elphidium crispum, Ammonia beccarii, and subordinately by Quinqueloculina sp1 and Heterolepa dutemplei. All sampling sites showed remarkable similarity in the Foraminiferal assemblages, and the Oued Nigro station is considered the wealthiest and densest site, whereas Oued Martil records the lowest values of those parameters. On the other hand, the Sample from M'diq presents the lowest diversity index even if it is the second in terms of density. The faunistic analysis had also allowed the observation of some morphological abnormalities only found in the Oued Nigro station, affecting some individuals' tests. A small-sized chamber mainly manifests the abnormal appearances in the spiral whorls and calcification defects in the calcareous wall.
Assessment of Sentinel-1A/B SAR Derived Ocean Wind Speeds against HY-2B Scatterometer in the Presence of Ocean Swells
Authors: Wang He , Shi Chaoying , Zhu Jianhua
Published: August 2021

Sentinel-1A/B satellites operating in wave mode provide ocean winds dataset on a continuous and global basis. In this study, wind speeds derived from Sentinel-1A/B wave mode imagery from November 2018 to October 2020 are evaluated against HSCAT scatterometer aboard Chinese satellite HY-2B. Here, due to the close equatorial crossing times between Sentinel-1 and HY-2B, the spatio-temporal criteria of 50 km and 30 min yield large amount match-ups. Comparison results show a good agreement between wind speeds derived from the two types of radars: synthetic aperture radar and scatterometer. Impact of the presence of pure swell on the evaluation results is also discussed.
Ku-band 500W Amplitude-phase Coherence Pulsed MPM for Ocean Exploration
Authors: Huang Weibo , Yang Fei , Li Hui , Chen Qianwen , Fu Hao
Published: August 2021

The spatial high-resolution synthetic aperture radar (SAR) for ocean exploration puts forward higher requirement for output power and amplitude-phase consistency of the pulsed TWT amplifier. The kW class pulsed TWT amplifier based on broadband power combining is the key technology for space SAR applications. In this paper, the factors affecting the amplitude and phase consistency of MPM are studied, and a phase consistency compensation circuit was designed to improve the phase consistency of multiple sets of products. A microwave power model (MPM) with dual TWTs output integrated architecture was proposed which consists of two short travelling wave tubes (TWT), two solid-state power amplifiers (SSPA), and an electronic power conditioner (EPC). More than 45% efficiency is achieved in 15% duty cycle within 600 MHz bandwidth, and the phase consistency was less than ± 5 degrees.With the improvement of synthesis efficiency, higher synthesis power and higher sensitivity of ocean wide scanning and detection can be obtained
Optimization of the Pre-treatment Method for the Determination of 9 Organophosphorus Pesticide Residues in Cabbage by Gas Chromatography
Authors: Guo Siya , Wang Xiaoyan , Zhang Zongyi , Zheng Hongwei , Guo Lei
Published: August 2021

The purpose of this study was to optimize the pre-treatment process for the detection of 9 organophosphorus pesticide residues in cabbage by gas chromatography, and to conduct a comparative experiment between this method and the standard method NY/T 761-2008 of the Ministry of Agriculture. The results show that the optimized pre-treatment method is to use 10 mL acetonitrile as the extractant, 150 mg N-propyl ethylenediamine (PSA) and 15 mg graphitized carbon black (GCB) as the purification agent, which can reduce the use of extractant and inorganic salt in the pre-treatment process, increase the recovery and detection limit, reduce the matrix effect and cost of instrument maintenance.
Research on the Settlement Performance of Flocculants on the Sediment of Mine River
Authors: Zhou Haiyan , Tang Zeheng , Li Guoqing , Dai Xiangrong
Published: August 2021

In view of adding different flocculant to the mine river sediment, the influence of different flocculants on the sedimentation performance of the mine river sediment was investigated. The experimental results show that the selected flocculant, cationic polyacrylamide (CPAM), has an evident effect on the flocculation and settlement of the mine river sediment. The final flocculation effect was enhanced with faster settling speed. The flocculation effect was optimized when 10 mL CPAM flocculant (0.2wt%) was added, followed by 3 minutes of stirring. The dewatering effect of the flocculated sediment can be enhanced with decreased solid content of the sediment.
Flow Structures of Submerged Gas Jet in Liquid Currents
Authors: Dong Ping , Cheng Dong , Jing Huixiang , Li Guanghua , Lu Bingju , Wang Ximeng
Published: August 2021

The flow structure of the submerged gas jet in liquid currents is important to engineering applications. In the present study, the development of a submerged gas jet subjected to liquid current is experimentally investigated to evaluate the effects of the current on the underwater gas jet evolution. A full-scale experimental setup is designed for submerged gas jet release and dispersion in the liquid currents with different velocities. The flow structures of the gas jet are captured by shadow photography combined with a high speed video camera. The experimental images are processed to extract the parameters and perform Proper Orthogonal Decomposition (POD) analysis to reveal the characteristics of different modes standing for different flow structures. It turns out that the flow structures of the gas jets submerged in liquid currents with different velocities are affected by the liquid currents and gas jet pulsation, and the analysis will provide credible assessment and opportunity to take prompt response to control potential accidents caused by the submerged gas jet release in liquid current.
A modified Perry-type derivative-free projection method for solving large-scale nonlinear monotone equations
Authors: Koorapetse M. , Kaelo P. , Kooepile-Reikeletseng S.
Published: August 2021

In this paper, a new modified Perry-type derivative-free projection method for solving large-scale nonlinear monotone equations is presented. The method is developed by combining a modified Perry’s conjugate gradient method with the hyperplane projection technique. Global convergence and numerical results of the proposed method are established. Preliminary numerical results show that the proposed method is promising and efficient compared to some existing methods in the literature.
225 Jahre Homöopathie: vom Auf und Ab einer „wissenschaftlichen Anomalie“
Authors: Lucae Christian
Published: August 2021

Das diesjährige Jubiläum der Homöopathie scheint nicht nur von den Schlagzeilen der Coronapandemie überschattet zu werden, sondern auch aufgrund der allgemeinen Homöopathie-Baisse der letzten Jahre wenig Beachtung zu finden. Dabei ist die 225-jährige Geschichte der Homöopathie durchaus spannend und abwechslungsreich: von der Frühzeit über die erste Schülergeneration Hahnemanns, die Blütezeit in Amerika bis in die 2. Hälfte des 19. Jahrhunderts, den Niedergang mit Aufkommen einer wissenschaftlichen Medizin, eine weitere produktive Phase Anfang des 20. Jahrhunderts mit der wissenschaftlich-kritischen Richtung, wiederum eine Zäsur bis in die 1950er-Jahre, schließlich eine Blütezeit seit den 1970er-Jahren mit Entwicklung verschiedener Schulen und Strömungen weltweit – bis hin zum allmählichen Niedergang in den letzten 15 Jahren. Bei dieser Wellenbewegung zwischen Begeisterung und Ablehnung waren je nach zeitgeschichtlichem Hintergrund viele unterschiedliche, aber auch manch wiederkehrende Faktoren im Spiel, die für ein Auf und Ab gesorgt haben.
Present Limitations of Artificial Intelligence in the Emergency Setting – Performance Study of a Commercial, Computer-Aided Detection Algorithm for Pulmonary Embolism
Authors: Müller-Peltzer Katharina , Kretzschmar Lena , Negrão de Figueiredo Giovanna , Crispin Alexander , Stahl Robert , Bamberg Fabian , Trumm Christoph Gregor
Published: August 2021

Purpose Since artificial intelligence is transitioning from an experimental stage to clinical implementation, the aim of our study was to evaluate the performance of a commercial, computer-aided detection algorithm of computed tomography pulmonary angiograms regarding the presence of pulmonary embolism in the emergency room.

Materials and Methods This retrospective study includes all pulmonary computed tomography angiogram studies performed in a large emergency department over a period of 36 months that were analyzed by two radiologists experienced in emergency radiology to set a reference standard. Original reports and computer-aided detection results were compared regarding the detection of lobar, segmental, and subsegmental pulmonary embolism. All computer-aided detection findings were analyzed concerning the underlying pathology. False-positive findings were correlated to the contrast-to-noise ratio.

Results Expert reading revealed pulmonary embolism in 182 of 1229 patients (49 % men, 10–97 years) with a total of 504 emboli. The computer-aided detection algorithm reported 3331 findings, including 258 (8 %) true-positive findings and 3073 (92 %) false-positive findings. Computer-aided detection analysis showed a sensitivity of 47 % (95 %CI: 33–61 %) on the lobar level and 50 % (95 %CI 43–56 %) on the subsegmental level. On average, there were 2.25 false-positive findings per study (median 2, range 0–25). There was no significant correlation between the number of false-positive findings and the contrast-to-noise ratio (Spearman’s Rank Correlation Coefficient = 0.09). Soft tissue (61.0 %) and pulmonary veins (24.1 %) were the most common underlying reasons for false-positive findings.

Conclusion Applied to a population at a large emergency room, the tested commercial computer-aided detection algorithm faced relevant performance challenges that need to be addressed in future development projects.

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Safety Aspects of Perinatal Ultrasound
Authors: Sande Ragnar , Jenderka Klaus-Vitold , Moran Carmel M. , Marques Susana , Jimenez Diaz J. F. , ter Haar Gail , Marsal Karel , Lees Christoph , Abramowicz Jacques S. , Salvesen Kjell Åsmund , Miloro Piero , Dall’Asta Andrea , Brezinka Christoph , Kollmann Christian
Published: August 2021

Ultrasound safety is of particular importance in fetal and neonatal scanning. Fetal tissues are vulnerable and often still developing, the scanning depth may be low, and potential biological effects have been insufficiently investigated. On the other hand, the clinical benefit may be considerable. The perinatal period is probably less vulnerable than the first and second trimesters of pregnancy, and ultrasound is often a safer alternative to other diagnostic imaging modalities. Here we present step-by-step procedures for obtaining clinically relevant images while maintaining ultrasound safety. We briefly discuss the current status of the field of ultrasound safety, with special attention to the safety of novel modalities, safety considerations when ultrasound is employed for research and education, and ultrasound of particularly vulnerable tissues, such as the neonatal lung. This CME is prepared by ECMUS, the safety committee of EFSUMB, with contributions from OB/GYN clinicians with a special interest in ultrasound safety.
DeGIR Quality Report 2019: Report on the treatment quality of minimally invasive methods – Interventional therapy (EVAR) of abdominal aortic aneurysms
Authors: Frenzel Felix , Bücker Arno , Paprottka Philipp , Nadjiri Jonathan , Mahnken Andreas H. , Massmann Alexander , Minko Peter , Heuser Lothar J.
Published: August 2021

Purpose To analyze the quality of endovascular aortic aneurysm repair using the data of the DeGIR quality management system. Comparison of data between 2011 and 2019.

Materials and Methods A retrospective analysis of all data registered in the DeGIR quality management system of the year 2019 was performed regarding the treatment quality for endovascular aortic aneurysm repair. Registration of data was voluntary. As quality parameters indication, treatment process data and quality of results were examined. The latter was judged by treatment success, complication rates and radiation exposure.

Results Out of 189 590 data sets overall 1639 cases of EVAR were registered; compared to 2011 this was an increase of 472 cases. 5.9 % of these cases encompassed emergency treatments. The most frequent indication was an abdominal aneurysm with 72 % of cases. In 54 % of cases, the aortic diameter ranged 50–70 mm. The rates for technical success, over all complications and major complications were 92.8 %, 6.7 % and 6.0 % respectively for all EVAR including emergency indications. In general, EVAR yielded a mortality rate of 1.2 % while emergency procedures had a mortality rate of 7.3 %. Median dose area product and fluoroscopy time were 10 503 cGy × cm2 and 20 minutes respectively at a mean procedure time of 114 minutes.

Conclusion Data analysis of the DeGIR quality management system persistently showed a very high technical success rate for endovascular aortic aneurysm repair performed by interventional radiologists accompanied by a low complication rate.

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Citation Format
Licencia parental durante la educación y la práctica en medicina: 35 años de análisis bibliométrico
Authors: Roa Daisy Ximena , Riveros Silvia , Saenz Maria Paula , Duque Joan Stefany , Sanchez Catalina , Solano Catalina
Published: August 2021

Objetivos La cantidad de mujeres en especialidades médico-quirúrgicas ha aumentado. Para nuestro conocimiento, no existen políticas que reglamenten las licencias parentales en nuestro país, que permitan a las mujeres que se desempeñan en esas especialidades vivir dicho periodo digna y equiparablemente con quienes han elegido otras carreras. Nuestro objetivo, es evaluar las publicaciones con respecto a la regulación y al apoyo a los procesos de maternidad y lactancia de los médicos.

Metodos Se realizó una revisión de la literatura, de los últimos 35 años en Medline a través de Fabumed, PubReminer y Scopus, utilizando los términos Mesh: “parental leave” y “physicians”. Se incluyeron todas las publicaciones sobre licencia de maternidad en médicos, de 1984 a 2019. Se hizo un análisis bibliométrico descriptivo retrospectivo de dichos artículos y un análisis de mapeo bibliométrico utilizando el programa de software: VOSviewer. Se realizó un análisis estadístico descriptivo de los datos obtenidos.

Resultados Encontramos 182 publicaciones desde 1984 hasta 2019. Detectamos dos picos de publicación, en los años 1992 y 2018. El 39,6% de las publicaciones está concentrado en 20 revistas, nueve con factor de impacto mayor a 3. La mayoría de las publicaciones (85%) se encontraron en inglés y se originaron en 12 países.

Conclusiones Aún no hay suficientes publicaciones para generar consenso en cuanto a aspectos relacionados con la reglamentación de la licencia de maternidad y lactancia en cirujanas. La estandarización de políticas, optimiza el ejercicio de la especialidad al mejorar el grado de satisfacción de los involucrados.
Effect of Resistance Training and Diet Intake on Spleen Structure of Ovariectomized Wistar Rats
Authors: Santana Erika Steffany dos Santos , de Oliveira Carolinne Alves , Lima Francisca Iranni Alves , Nucci Ricardo Aparecido Baptista , Fonseca Fernando Luiz Affonso , Maifrino Laura Beatriz Mesiano
Published: August 2021

Introduction Exercise is a key factor in immunity which may be affected by a different diet intake. Thus, we aimed to analyze the effects of diet intake and resistance training on spleen structure of ovariectomized female animals.

Materials and Methods Female Wistar rats were divided into eight experimental groups: sedentary and nonovariectomized animals plus vegetable protein diet (CVS) or animal protein diet (CAS); trained and nonovariectomized rats plus vegetable protein diet (CVT) or animal protein diet (CT); sedentary and ovariectomized groups plus vegetable protein diet (VOS) or animal protein diet (AOS); and trained and ovariectomized animals plus vegetable protein diet (VOT) or animal protein diet (AOT).

Results Groups submitted to both animal protein diet and resistance training, mainly ovariectomized groups, presented a great variability of collagen fibers type III, white pulp, and follicle structure in relation to the other spleen constituents.

Conclusion Resistance training with a vegetable protein diet may play a key factor to maintain spleen’s immune responses across age. However, animal protein diet is suggested to decrease spleen’s immune activity.
TIVA versus Inhalational Agents for Pediatric Cardiac Intensive Care
Authors: Kashav Ramesh Chand , Kohli Jasvinder Kaur , Magoon Rohan ,   ItiShri
Published: August 2021

The field of pediatric intensive care has come a long way, especially with the recognition that adequate sedation and analgesia form an imperative cornerstone of patient management. With various drugs available for the same, the debate continues as to which is the better: total intravenous anesthesia (TIVA) or inhalational agents. While each have their own advantages and disadvantages, in the present era of balance toward the IV agents, we should not forget the edge our volatile agents (VAs) might have in special scenarios. And ultimately as anesthesiologists, let us not forget that be it knob and dial, or syringe and plunger, our aim is to put pain to sleep and awaken a new faith to breathe.
Immature Platelet Fraction and COVID-19: Maturing prognostic links!
Authors: Jose Jes , Magoon Rohan , Makhija Neeti
Published: August 2021

Prompted by the combination of an ever-evolving comprehension of the platelet activation as a pivotal perpetuator of an ongoing systemic inflammatory process and an encouraging literature on the prognostic role of immature platelet fraction (IPF) in septic and prothrombotic settings, we present an elaborated account of the possible prognostic links between IPF and Coronavirus disease 2019 (COVID-19).
Large Right Atrial Myxoma Masquerading as Malignancy
Authors: V. Bharath , Hote Milind Padmakar
Published: August 2021

A 57-year-old female presented to emergency with features of right heart failure. On evaluation, she was found to have a large mass occupying right atrium (RA) completely and protruding into right ventricle through tricuspid valve. Intraoperatively, mass was seen arising from RA free wall with stony hard consistency. Histopathology revealed it to be myxoma. We present this case for the rare presentation of myxoma masquerading as malignancy.
Characterization of Darboux transformations for quantum systems with quadratically energy-dependent potentials
Authors: Schulze-Halberg Axel
Published: August 2021

We construct three classes of higher-order Darboux transformations for Schrödinger equations with quadratically energy-dependent potentials by means of generalized Wronskian determinants. Particular even-order cases reduce to the Darboux transformation for conventional (energy-independent) potentials. Our construction is based on an adaptation of the results for coupled Korteweg–de Vries equations [N. V. Ustinov and S. B. Leble, J. Math. Phys. 34, 1421 (1993)].
New mounting mechanism for cryogenically cooled thin crystal x-ray optics in high brightness high repetition rate free-electron laser applications
Authors: Qu Zhengxian , Borzenets Valery , Zhou Guanqun , Ma Yanbao , Wu Juhao
Published: August 2021

We present a new mounting design for thin crystal optics with cryogenic cooling compatibility. We design a crystal geometry with two symmetric strain-relief cuts to mitigate the distortion from mounting. We propose to sputter gold onto the crystal and the holder to ensure excellent thermal contact and sufficient mechanical bonding. The system is analyzed and verified by finite element analysis to have an acceptable level of strain due to mounting. The thermal performance of this mounting scheme is validated in an example cryogenic cooling system and the results indicate a tolerance of power density up to ∼1 kW/mm2.
A generic theoretical approach for estimating bandgap bounds of metamaterial beams
Authors: Jian Yupei , Hu Guobiao , Tang Lihua , Xu Jiawen , Aw Kean C.
Published: August 2021

The bandgap phenomenon in metamaterials has attracted much research interest for controlling structural vibrations. To tailor the bandgap for applications in a specific frequency range, analytical tools for bandgap bound estimations are critically important. This work presents a generic theoretical approach for fast estimation of the bandgap bounds. Starting from the lattice metamaterial systems, we develop the procedure and provide the analytical bound expressions based on a hypothesis of extreme points in the band structure of metamaterial systems. The proposed approach for the lattice system is verified by the results of transmittance analysis. Subsequently, to explore the fidelity of the proposed approach on continuous metamaterial systems, three typical metamaterial beams (metabeams) have been investigated: a metabeam with mechanical local resonators, a piezoelectric metabeam with shunt resonant circuits, and a hybrid metabeam. Finite element analysis is performed to verify the theoretical expressions of bandgap bounds derived using the proposed approach. With the verified bound expressions, bandgap tailoring and optimization are further investigated. In summary, the developed theoretical approach is generic and offers a promising technique for bandgap estimation of metamaterial systems integrated with various types of resonators.
Magneto-spectroscopy investigation of InAs/InAsSb superlattices for midwave infrared detection
Authors: Krizman G. , Carosella F. , Bermejo-Ortiz J. , Philippe A. , Rodriguez J. B. , Perez J.-P. , Christol P. , de Vaulchier L.-A. , Guldner Y.
Published: August 2021

Raising the operating temperature of the midwave infrared (MWIR) cameras up to 150 K without penalizing the performances of the photodetectors is one of the main challenges of the domain. Moreover, extending the range of detection up to 5 μm brings many advantages. Ga-free InAs/InAsSb superlattice based devices have been recently fabricated and they showed the first realization of these objectives. However, the band parameters (band offsets, effect of strain, effective mass) of this system have not been determined accurately, thus limiting the understanding and the prediction of the electronic properties of the devices. In this work, we determined the relevant parameters via magnetoabsorption measurements performed on dedicated superlattices. Interband magneto-optical transitions lead to an accurate mapping of the Landau levels. The Landau level energies have been calculated using an 8-band k⋅ p model, and the comparison with the experimental data provided a clear description of the type 2 superlattice miniband structure at 4.2 and 150 K, as well as its MWIR absorbance.
Multiple solitary wave interactions
Authors: Nakayama Keisuke , Tsuji Hidekazu
Published: August 2021

Theoretical solutions of two-soliton resonance show the possibility that the amplitude of soliton resonance is four times as large as the incident solitary wave at the critical angle. The two-soliton interaction with a symmetrical configuration is generally categorized into (3142)-type and (2143)-type (O-type). Previous studies demonstrated that amplification factors of (3142)-type and O-type are successfully reproduced by using a function of the modified Miles' prediction, κ, in which (3142)-type and O-type correspond to 0<κ<1 and κ>1. However, a train of solitary waves often occurs in shallow water, resulting in multiple solitary wave interactions. Therefore, it is necessary to investigate the interaction of multiple solitary waves due to soliton resonance. We, thus, applied theoretical solutions to analyze the interaction of multiple solitary waves, which was validated by using numerical simulations based on the variational principle. It was revealed that the second and the subsequent soliton resonances are O-type when κ is larger than zero.
Numerical study on oscillatory propagation dynamics and physics near the limits of planar freely propagating premixed flames
Authors: Zhang Yi , Kang Yinhu , Lu Xiaofeng , Wang Quanhai
Published: August 2021

An oscillatory phenomenon of the freely propagating premixed flames for dimethyl ether–air mixtures at near-limit conditions was systematically analyzed to understand the underlying physicochemical processes that control the oscillation and extinction of hot-lean flames. The flame oscillation dynamics and extinction mechanism were first investigated using the analyses of flame oscillating structure and phase function. It was found that the leading cool-flame front and tailing hot-flame front present a significant separation during the oscillatory propagation, and the formation of flame oscillation was the consequence of the interaction between the two flame fronts which can be explained as the competition of reactions between low-, intermediate-, and high-temperature pathways. Meanwhile, due to the excessive heat losses of the lower half period, the flame will eventually extinguish in the divergent oscillating process. Furthermore, the key processes in the flame oscillation were further revealed by chemical explosive mode analysis-based diagnosis. The results show that the oscillations are primarily originated from the species and reactions of the intermediate-temperature pathway, including H2O2 and CH2O, and chain-branching/-termination reactions. These key processes eventually lead to the flame oscillatory extinction presenting an O(2) frequency.
The study of negative needle-to-plane corona discharge with photoionization under various air pressures
Authors: Lu B. X. , Song L. J.
Published: August 2021

The characteristics of negative corona discharge in practical applications are strongly dominated by environmental parameters, such as air pressure. An axisymmetric hydrodynamic drift-diffusion model considering the effect of air pressure and photoionization has been established in this study based on a traditional needle-to-plate configuration in dry air at room temperature. Trichel pulses, electron density, negative ion density, and electric field distribution during discharge are discussed to investigate the effect of air pressure and photoionization. The results show that the magnitude of the first Trichel pulse without photoionization decreases from 0.92 to 0.6 mA with the increase in the air pressure (0.7–1.1 atm). However, the magnitude of the third Trichel pulse without photoionization increases from 0.28 to 0.55 mA with the increase in the air pressure (0.7–0.9 atm), while it decreases from 0.55 to 0.47 mA with the increase in the air pressure (0.9–1.1 atm). Moreover, the decrease in the air pressure could result in faster movement of charged particles. The role of photoionization under different air pressures is also discussed by numerical simulations.
Bubble dynamics and dry spot formation during boiling on a hierarchical structured surface: A lattice Boltzmann study
Authors: Yu Y. , Li Q. , Qiu Y. , Huang R. Z.
Published: August 2021

In this paper, the bubble dynamics and the mechanism of dry spot formation during boiling on a two-level hierarchical structured surface are numerically investigated using a three-dimensional thermal multiphase lattice Boltzmann model with liquid–vapor phase change. The hierarchical structured surface consists of three parts: a smooth surface basement, primary pillars on the basement, and secondary pillars overlaid on the primary pillars. It is found that the boiling heat transfer on the hierarchical structured surface is significantly dependent on the bubble departure frequency and the dry area fraction, which are in turn affected by the structural parameters of secondary pillars. Increasing the height or width of the secondary pillars is found to effectively increase the bubble departure frequency, but it may also enlarge the size of dry spots on the hierarchical structured surface. The numerical investigation shows that, in order to prevent the formation of dry spots on the hierarchical structured surface, an effective approach is to reduce the proportion of the contact line on the lateral walls of secondary pillars to the whole contact line, which can be realized by reducing the area of the lateral walls of secondary pillars or appropriately increasing the secondary pillar spacing. The optimum boiling performance on the hierarchical structured surface is found to be achieved under the situation that the bubble departure frequency is sufficiently high, but the dry spot area is as small as possible.
Investigations of the sheath in a dual-frequency capacitively coupled rf discharge by optically trapped microparticles
Authors: Schleitzer J. , Schneider V. , Kersten H.
Published: August 2021

The sheath of a dual-frequency capacitively coupled rf discharge has been investigated with microparticles as probes based on two different methods: by the first method, intensity profiles of the emitted light of the discharge and the scattered light of the microparticles are used to study the effects of phase variation between the fundamental frequency (13.56 MHz) and its first harmonic (27.12 MHz) or a change in the dc self-bias, respectively, on the expansion of the sheath and the levitation height of microparticles in the sheath. These measurements show that the sheath width as well as the levitation height of the microparticles correlates with the dc self-bias as a function of the phase between the applied voltage harmonics. By a second method, profiles of the force acting on an optically trapped microparticle in an optical tweezer in the sheath were measured. On the basis of these force profiles, the strength of the electric field force as a function of pressure and the dependency on the distance of the probe to the rf electrode as well as the extent of the sheath are determined in both a single- and a dual-frequency discharge. From the results, it can be deduced that the sheath thickness and the electric field force in a dual-frequency discharge are influenced by both excitation frequencies and, thus, differ from a single-frequency discharge.
Investigation of vertical tail buffeting alleviation controlled by nanosecond plasma actuators
Authors: Chen Sinuo , Shi Zhiwei , Zhao Zijie , Geng Xi , Chen Zhen
Published: August 2021

An experimental study was conducted with the aim of alleviating the vertical tail buffeting of a 55° delta wing using pulsed nanosecond dielectric barrier discharge plasma actuators. The flow physics in the event of wing stall, flow reattachment, vortex breakdown, shear layer under plasma actuation were obtained and analyzed, and results indicate that plasma actuation promotes flow attachment and manipulates the shear layer. The acceleration results indicate that the structural response of the vertical tail increases with an increasing angle of attack, and the first bending mode response increases most significantly at the post-stall angle. Manipulation of flow field by plasma actuation produces a considerable reduction in buffeting response and mainly controls the first bending mode. The characteristics of velocity fluctuations show two important factors affecting buffeting: the redistribution of loads and the spectrum change of fluctuations, both of which are related to the movement of the impingement point of the shear layer onto the vertical tail controlled by plasma actuation. Theoretical analysis indicates that the impingement point moving downward in the vertical direction of the vertical tail under plasma actuation is the main reason for reduction of the first bending mode response.
Complete-active-space extended Koopmans theorem method
Authors: Davidson Ernest R. , Ortiz Joseph Vincent , Staroverov Viktor N.
Published: August 2021

The complete-active-space (CAS) extended Koopmans theorem (EKT) method is defined as a special case of the EKT in which the reference state is a CAS configuration interaction (CI) expansion and the electron removal operator acts only on the active orbitals. With these restrictions, the EKT is equivalent to the CI procedure involving all hole-state configurations derived from the active space of the reference wavefunction and has properties analogous to those of the original Koopmans theorem. The equivalence is used to demonstrate in a transparent manner that the first ionization energy predicted by the EKT is in general not exact, i.e., not equal to the difference between the full CI energies of the neutral and the ion, but can approach the full CI result with arbitrary precision even within a finite basis set. The findings also reconcile various statements about the EKT found in the literature.
Experimental investigation on the influence of bristle lay angle on the leakage characteristics of low hysteresis brush seals
Authors: Hu Yaping , Chen Wenyang , Li Pengfei , Li Ning , Zhou Kun , Pan Jun
Published: August 2021

The leakage characteristics and hysteresis effect were experimentally studied on three test pieces of a low hysteresis brush seal with bristle lay angles of 40°, 45°, and 50°. The results showed that under the same conditions, the leakage coefficient is the largest and smallest when the bristle lay angles are 50° and 45°, respectively. The leakage coefficient increases significantly when the bristle lay angle exceeds 45°. The leakage coefficient increases with pressure differential and then is almost unchanged when it exceeds 0.2 MPa. When the rotating speed increases, the leakage coefficient decreases slightly. The rising and dropping of pressure differential caused a distinct leakage hysteresis effect, which is the weakest when the bristle lay angle is 45°. In addition, the hysteresis effect in a rotating state is weaker than that in a static state. The hysteresis effect due to rising and dropping of rotating speed is very weak with a pressure differential of 0.1 MPa. As the pressure differential increases to 0.3 MPa, the hysteresis effect is slightly enhanced. The overall performance is optimal when the bristle lay angle is 45°.
Covalence and π-electron delocalization influence on hydrogen bonds in proton transfer process of o-hydroxy aryl Schiff bases: A combined NMR and QTAIM analysis
Authors: Zarycz M. Natalia C. , Schiel M. Ayelén , Angelina Emilio , Enriz Ricardo D.
Published: August 2021

Within the framework of the density functional theory approach, we studied the relationship between the chemical nature of intramolecular hydrogen bonds (HBs) and nuclear magnetic resonance (NMR) parameters, J-couplings and 1H-chemical shifts [δ(1H)], of the atoms involved in such bonds in o-hydroxyaryl Schiff bases during the proton transfer process. For the first time, the shape of the dependence of the degree of covalence in HBs on 1J(N–H), 1J(O–H), 2hJ(O–N), and δ(1H) during the proton transfer process in o-hydroxyaryl Schiff bases was analyzed. Parameters obtained from Bader’s theory of atoms in molecules were used to assess the dependence of covalent character in HBs with both the NMR properties. The influence of π-electronic delocalization on 2hJ(N–O) under the proton transfer process was investigated. 2hJ(O–N) in a Mannich base was also studied in order to compare the results with an unsaturated system. In addition, substituent effects on the phenolic ring were investigated. Our results indicate that the covalent character of HBs on both sides of the transition state undergoes a smooth exponential increase as the δ(1H) moves downfield. The degree of covalence of the N⋯H (O⋯H) bond increases linearly as 1J(N–H) (1J(O–H)) becomes more negative, even after reaching the transition state. Non-vanishing values of spin dipolar (SD) and paramagnetic spin orbital terms of 2hJ(O–N) show that π-electronic delocalization has a non-negligible effect on tautomeric equilibrium and gives evidence of the presence of the resonance assisted HB.Variation of the SD term of 2hJ(O–N) follows a similar pattern as the change in the para-delocalization aromaticity index of the chelate ring.
Stability of buoyancy-driven flow in a vertical channel with one heated wall
Authors: Zeraati Dizjeh S. , Brinkerhoff J.
Published: August 2021

The stability of the buoyancy-driven flow in a channel between an isothermal heated vertical wall and an adiabatic vertical wall is investigated by numerical integration of the derived two-dimensional stability equations for this type of buoyant flow. Stability calculations are carried out for a Prandtl number of 0.707 inside four vertical channels at Grashof numbers of 6.1×1010 and 1.49×1011 and with length-to-width aspect ratios of 8, 10, 40/3, and 20. The flow within the channel is numerically modeled by means of two-dimensional direct numerical simulations (DNSs), and the solved temperature and velocity fields are used as the base flow properties in the derived stability equations. Solutions of the stability equations yield the phase velocity, wave number, and growth rate for upper- and lower-branch neutrally stable disturbances, disturbances with maximum growth rates, and disturbances with phase velocities equal to the maximum velocity of the base flow inside the vertical channels. The predictions of the linear stability theory are compared with the disturbance growth observed in the simulated flow by means of a short-time Fourier transform of the velocity field computed from the DNS. The results show that while a range of disturbance wave numbers may be amplified in the channel, those that sustain the largest linear amplification have phase velocities equal to the peak velocity of the flow near the heated wall. The frequency of the most amplified disturbance increases linearly with the channel aspect ratio.
A 90 nm-CMOS broadband receiver with 10 dB conversion gain and 15 dB noise figure in 80–110 GHz suitable for multi-pixel imaging arrays
Authors: Chu-Chen Hsuan , Hsieh Kuan-Han , Hu Robert
Published: August 2021

This paper describes the latest development of a W-band 90 nm-CMOS receiver chip that is suitable for use in radio-astronomical multi-pixel imaging arrays and other broadband scientific instruments. This circuit includes an RF-low-noise amplifier (LNA), mixer, intermediate-frequency amplifier (IF-Amp), local-oscillator (LO) tripler, and driving amplifier. With a tripler integrated into the circuit, the incoming 80–110 GHz spectrum can be directly down-converted to 2–32 GHz by the applied 26 GHz LO signal. The system architecture will be presented, with the corresponding sub-circuits discussed in detail. In the on-wafer measurement at room temperature, this receiver has around 10 dB gain and 15 dB noise figure across the whole frequency range, with 400 mW power dissipation under 1.8 V DC bias. By adding a compound-semiconductor LNA in front of this CMOS receiver chip, compact low-noise receiver modules can be easily constructed and deployed.
On the incipient sediment suspension downstream of three-dimensional wall-mounted obstacles
Authors: Bhamitipadi Suresh Dhanush , Aju Emmanuvel Joseph , Pham Dat Thanh , Jin Yaqing
Published: August 2021

The incipient sediment suspension downstream of a thin square tab with various inclination angles was fundamentally described using experiments and theoretical arguments. Volumetric particle tracking velocimetry and particle image velocimetry were applied to measure the sediment particle distributions and wake flows under various incoming velocities and obstacle inclination angles. Results show that suspension of sediments occurred downstream of the obstacles due to the enhanced local turbulence intensities. Although the sediment volumetric fraction was mostly determined by the variation of wake turbulence kinetic energy under low inclination angles (i.e., obstacles nearly parallel to incoming flow), this was not the case under high inclination angle counterparts where distinct downward velocities dominated the wake region and suppressed the sediment suspension. This led to the decrease of sediment volumetric fraction with the growth of tab inclination at high inclination angles. Supported by flow measurements, a revised Rouse number was introduced which allows to quantitatively integrate the coupled influence of turbulence mixing load and vertical flows across various incoming velocities and inclination angles.
Cascaded superconducting junction refrigerators: Optimization and performance limits
Authors: Kemppinen A. , Ronzani A. , Mykkänen E. , Hätinen J. , Lehtinen J. S. , Prunnila M.
Published: August 2021

We demonstrate highly transparent silicon–vanadium and silicon–aluminum tunnel junctions with relatively low sub-gap leakage current and discuss how a trade-off typically encountered between transparency and leakage affects their refrigeration performance. We theoretically investigate cascaded superconducting tunnel junction refrigerators with two or more refrigeration stages. In particular, we develop an approximate method that takes into account self-heating effects but still allows us to optimize the cascade a single stage at a time. We design a cascade consisting of energy-efficient refrigeration stages, which makes cooling of, e.g., quantum devices from above 1 K to below 100 mK a realistic experimental target.
Substitution, delegation or addition? A discussion of workforce skill mix in computed tomography
Authors: Harris Martine Ann , Snaith Bev
Published: August 2021

Abstract A letter to the Editor in response to the recently published article by Cartwright et al. (AHR, https://doi.org/10.1071/AH20118) on the implication of workforce models on efficiency and staff well-being in a computed tomography department.
Large-scale drivers of Australian east coast cyclones since 1851
Authors: Browning Stuart A. , Goodwin Ian D.
Published: August 2021

Subtropical maritime low-pressure systems are one of the most complex and destructive storm types to impact Australia’s eastern seaboard. This family of storms, commonly referred to as East Coast Cyclones (ECC), is most active during the late autumn and early winter period when baroclinicity increases in the Tasman Sea region. ECC have proven challenging to forecast at both event and seasonal timescales. Storm activity datasets, objectively determined from reanalyses using cyclone detection algorithms, have improved understanding of the drivers of ECC over the era of satellite data coverage. In this study we attempt to extend these datasets back to 1851 using the Twentieth Century Reanalysis version 2c (20CRv2c). However, uncertainty in the 20CRv2c increases back through time due to observational data scarcity, and individual cyclones counts tend to be underestimated during the 19th century. An alternative approach is explored whereby storm activity is estimated from seasonal atmosphere-ocean circulation patterns. Seasonal ECC frequency over the 1955 to 2014 period is significantly correlated to regional sea-level pressure and sea surface temperature (SST) patterns. These patterns are used to downscale the 20CRv2c during early years when individual events are not well simulated. The stormiest periods since 1851 appear to have been 1870 to the early 1890s, and 1950 to the early 1970s. Total storm activity has been below the long-term average for most winters since 1976. Conditions conducive to frequent ECC events tend to occur during periods of relatively warm SST in the southwest Pacific typical of negative Interdecadal Pacific Oscillation (IPO-ve). Extratropical cyclogenesis is associated with negative Southern Annular Mode (SAM-ve) and blocking in the southern Tasman Sea. Subtropical cyclogenesis is associated with SAM+ve and blocking in the central Tasman Sea. While the downscaling approach shows some skill at estimating seasonal storm activity from the large-scale circulation, it cannot overcome data scarcity based uncertainties in the 19th century when the 20CRv2c is effectively unconstrained throughout most of the southern hemisphere. Storm frequency estimates during the 19th century are difficult to verify and should be interpreted cautiously and with reference to available documentary evidence.
East Coast Lows and the Pasha Bulker storm - lessons learned nine years on
Authors: Verdon-Kidd Danielle C , Kiem Anthony S , Willgoose Garry R
Published: August 2021

East Coast Lows (ECLs) are intense low pressure systems that form several times a year off the east coast of Australia. When these systems occur close to land they can cause major damage to infrastructure and communities due to gale force winds, intense rainfall, storm surge and coastal erosion. In June 2007, Newcastle and Central Coast regions of New South Wales (NSW) experienced severe weather and subsequent flash flooding. The ‘Pasha Bulker’ storm, as it has become known, was one of the most significant meteorological events in Australia’s history, with large economic losses and social disruption due to the loss of critical infrastructure. This paper provides background information on the meteorology of the event, the impact of the Pasha Bulker storm and a discussion of the lessons learned from the event and subsequent adaptation strategies employed. The paper also provides important reflections, at both regional and national level, on the Pasha Bulker storm and other similar storm events. Lessons for all levels of government and community groups are discussed, including preparedness before the event, actions during the event, and recovery processes post-event. From this, recommendations and conclusions are made on actions and strategies to increase adaptive capacity and resilience to extreme weather events like ECLs.
A bias corrected WRF mesoscale fire weather dataset for Victoria, Australia 1972-2012
Authors: Brown Timothy , Mills Graham , Harris Sarah , Podnar Domagoj , Reinbold Hauss , Fearon Matt
Published: August 2021

Climatology data of fire weather across the landscape can provide science-based evidence for informing strategic decisions to ameliorate the impacts (at times extreme) of bushfires on community socio-economic wellbeing and to sustain ecosystem health and functions. A long-term climatology requires spatial and temporal data that are consistent to represent the landscape in sufficient detail to be useful for fire weather studies and management purposes. To address this inhomogeneity problem for analyses of a variety of fire weather interests and to provide a dataset for management decision-support, a homogeneous 41-year (1972-2012), hourly interval, 4 km gridded climate dataset for Victoria has been generated using a combination of mesoscale modelling, global reanalysis data, surface observations, and historic observed rainfall analyses. Hourly near-surface forecast fields were combined with Drought Factor (DF) fields calculated from the Australian Water Availability Project (AWAP) rainfall analyses to generate fields of hourly fire danger indices for each hour of the 41-year period. A quantile mapping (QM) bias correction technique utilizing available observations during 1996-2012 was used to ameliorate any model biases in wind speed, temperature and relative humidity. Extensive evaluation was undertaken including both quantitative and case study qualitative assessments. The final dataset includes 4-km surface hourly temperature, relative humidity, wind speed, wind direction, Forest Fire Danger Index (FFDI), and daily DF and Keetch-Byram Drought Index (KBDI), and a 32-level full three-dimensional volume atmosphere.