bluuebunny/crossref_metadata_2025 huggingface dataset:
A Two-Component regulatory system with opposite effects on glycopeptide antibiotic biosynthesis and resistance
Authors: Alduina Rosa , Tocchetti Arianna , Costa Salvatore , Ferraro Clelia , Cancemi Patrizia , Sosio Margherita , Donadio Stefano
Published: April 2020

The glycopeptide A40926, produced by the actinomycete Nonomuraea gerenzanensis, is the precursor of dalbavancin, a second-generation glycopeptide antibiotic approved for clinical use in the USA and Europe in 2014 and 2015, respectively. The final product of the biosynthetic pathway is an O-acetylated form of A40926 (acA40926). Glycopeptide biosynthesis in N. gerenzanensis is dependent upon the dbv gene cluster that encodes, in addition to the two essential positive regulators Dbv3 and Dbv4, the putative members of a two-component signal transduction system, specifically the response regulator Dbv6 and the sensor kinase Dbv22. The aim of this work was to assign a role to these two genes. Our results demonstrate that deletion of dbv22 leads to an increased antibiotic production with a concomitant reduction in glycopeptide resistance. Deletion of dbv6 results in a similar phenotype, although the effects are not as strong as in the Δdbv22 mutant. Consistently, quantitative RT-PCR analysis showed that Dbv6 and Dbv22 negatively regulate the regulatory genes (dbv3 and dbv4), as well as some dbv biosynthetic genes (dbv23 and dbv24), whereas Dbv6 and Dbv22 positively regulate transcription of the single, cluster-associated resistance gene. Finally, we demonstrate that exogenously added acA40926 and its precursor A40926 can modulate transcription of dbv genes but with an opposite extent: A40926 strongly stimulates transcription of the Dbv6/Dbv22 target genes while acA40926 has a neutral or negative effect on transcription of those genes. We propose a model in which glycopeptide biosynthesis in N. gerenzanensis is modulated through a positive feedback by the biosynthetic precursor A40926 and a negative feedback by the final product acA40926. In addition to previously reported control systems, this sophisticated control loop might help the producing strain cope with the toxicity of its own product. This work, besides leading to improved glycopeptide producing strains, enlarges our knowledge on the regulation of glycopeptide biosynthesis in actinomycetes, setting N. gerenzanensis and its two-component system Dbv6-Dbv22 apart from other glycopeptide producers.
Abdominal multi-organ auto-segmentation using 3D-patch-based deep convolutional neural network
Authors: Kim Hojin , Jung Jinhong , Kim Jieun , Cho Byungchul , Kwak Jungwon , Jang Jeong Yun , Lee Sang-wook , Lee June-Goo , Yoon Sang Min
Published: April 2020

Segmentation of normal organs is a critical and time-consuming process in radiotherapy. Auto-segmentation of abdominal organs has been made possible by the advent of the convolutional neural network. We utilized the U-Net, a 3D-patch-based convolutional neural network, and added graph-cut algorithm-based post-processing. The inputs were 3D-patch-based CT images consisting of 64 × 64 × 64 voxels designed to produce 3D multi-label semantic images representing the liver, stomach, duodenum, and right/left kidneys. The datasets for training, validating, and testing consisted of 80, 20, and 20 CT simulation scans, respectively. For accuracy assessment, the predicted structures were compared with those produced from the atlas-based method and inter-observer segmentation using the Dice similarity coefficient, Hausdorff distance, and mean surface distance. The efficiency was quantified by measuring the time elapsed for segmentation with or without automation using the U-Net. The U-Net-based auto-segmentation outperformed the atlas-based auto-segmentation in all abdominal structures, and showed comparable results to the inter-observer segmentations especially for liver and kidney. The average segmentation time without automation was 22.6 minutes, which was reduced to 7.1 minutes with automation using the U-Net. Our proposed auto-segmentation framework using the 3D-patch-based U-Net for abdominal multi-organs demonstrated potential clinical usefulness in terms of accuracy and time-efficiency.
Self-assembly of charged colloidal cubes
Authors: Rosenberg Margaret , Dekker Frans , Donaldson Joe G. , Philipse Albert P. , Kantorovich Sofia S.
Published: April 2020

In this work, we show how and why the interactions between charged cubic colloids range from radially isotropic to strongly directionally anisotropic depending on tuneable factors.
Surface-topology-controlled mechanical characteristics of triply periodic carbon Schwarzite foams
Authors: Gong Hao , Liu Jinjie , Xu Ke , Wu Jianyang , Li Yang
Published: April 2020

Carbon Schwarzites exhibit unique mechanical characteristics that are dominated by their topologies, rather than the mass density.
Multi‐objective coordinated dispatch of high wind‐penetrated power systems against transient instability
Authors: Xie Xuekuan , Xu Yan , Dong Zhao Yang , Zhang Yuchen , Liu Junwei
Published: April 2020

High‐level wind power penetration has significantly changed the power system's static and dynamic characteristics, which tends to decrease the overall system transient instability. This study proposes a multi‐objective preventive‐emergency coordinated control method against transient instability in the presence of uncertain wind power generation. This method optimally coordinates preventive control (PC) and emergency control (EC) to simultaneously minimise the total control cost and the expected stability margin. PC includes synchronous generator dispatch and wind farm power curtailment to reduce the overall percentage of renewable power to a safe level. EC adopts an emergency demand response scheme, in which the demand is immediately reduced for stabilising post‐contingency system and avoiding wide‐spread blackout. Wind power uncertainty is modelled through Taguchi's testing scenarios. The proposed method was verified on both New England 39‐bus system and Nordic‐32 system using industry‐grade dynamic models and simulation software. Simulation results verified that the proposed method can optimally balancing system control cost and system expected stability margin.
Robust multi‐lane detection method based on semantic discrimination
Authors: Zhong Yuzhong , Zhang Jianwei , Li Yingjiang , Geng Tianyu , Wang Maoning
Published: April 2020

Lane detection is the most basic part of automatic driving, driver assistance and violation‐detection systems. A lane detection method based on semantic discrimination is proposed to address the problems of diversity in illumination, occlusion and lack of prior knowledge about lane markings. Two symmetric ridge operators are designed to improve the precision of candidate‐pixel extraction. The double‐constrained random sample consensus method (DC‐RANSAC) introduces colour and geometric constraints into the lane fitting to reduce the number of iterations and improve the accuracy of the hypothetical model. Classifiers are added to further validate the hypothetical model and identify its underlying semantics. The proposed method was evaluated using two different data sets with various scenarios, including unclear lane markings, dense traffic, occlusion of vehicles, complex shadows, road surface markings, poor lighting conditions, and unknown number of lane markings. The detailed evaluations show that the detection rate of the proposed method is comparable with that of existing state‐of‐the‐art lane detection methods, whereas the precision rate is much higher. Moreover, the experiments prove the reliability of the proposed algorithm in lane marking semantic recognition.
Edge collapse and subsequent longitudinal accretion in filament S242
Authors: Yuan Lixia , Li Guang-Xing , Zhu Ming , Liu Tie , Wang Ke , Liu Xunchuan , Kim Kee-Tae , Tatematsu Ken’ichi , Yuan Jinghua , Wu Yuefang
Published: April 2020

Filament S242 is 25 pc long with massive clumps and YSO clusters concentrated in its end regions; it is considered a good example of edge collapse. We mapped this filament in the 12CO(1–0) and 13CO(1–0) lines. A large-scale velocity gradient along filament S242 has been detected; the relative velocity between the two end-clumps is ~3 km s−1, indicating an approaching motion between them. These signatures are consistent with the filament S242 being formed through the collapse of a single elongated entity, where an effect known as “gravitational focusing” drives the ends of the filament to collapse (edge collapse). Based on this picture, we estimate a collapse timescale of ~4.2 Myr, which is the time needed for a finite and elongated entity evolving to the observed filament S242. For the whole filament, we find that increases in surface densities lead to increases in velocity dispersion, which can be consistently explained as the result of self-gravity. We also calculated the contribution of longitudinal collapse to the observed velocity dispersion and found it to be the dominant effect in driving the gas motion near the end-clumps. We propose that our filament S242 is formed through a two-stage collapse model, where the edge collapse of a truncated filament is followed by a stage of longitudinal accretion toward the dense end-clumps.
Liverpool-Maidanak monitoring of the Einstein Cross in 2006–2019
Authors: Goicoechea L. J. , Artamonov B. P. , Shalyapin V. N. , Sergeyev A. V. , Burkhonov O. A. , Akhunov T. A. , Asfandiyarov I. M. , Bruevich V. V. , Ehgamberdiev S. A. , Shimanovskaya E. V. , Zheleznyak A. P.
Published: April 2020

Quasar microlensing offers a unique opportunity to resolve tiny sources in distant active galactic nuclei and study compact object populations in lensing galaxies. We therefore searched for microlensing-induced variability of the gravitationally lensed quasar QSO 2237+0305 (Einstein Cross) using 4374 optical frames taken with the 2.0 m Liverpool Telescope and the 1.5 m Maidanak Telescope. These gVrRI frames over the 2006–2019 period were homogeneously processed to generate accurate long-term multi-band light curves of the four quasar images A–D. Through difference light curves, we found strong microlensing signatures. We then focused on the analytical modelling of two putative caustic-crossing events in image C, finding compelling evidence that this image experienced a double caustic crossing. Additionally, our overall results indicate that a standard accretion disc accounts reasonably well for the brightness profile of UV continuum emission sources and for the growth in source radius when the emission wavelength increases: Rλ ∝ λα, α = 1.33 ± 0.09. However, we caution that numerical microlensing simulations are required before firm conclusions can be reached on the UV emission scenario because the VRI-band monitoring during the first caustic crossing and one of our two α indicators lead to a few good solutions with α ≈ 1.
Herpetofauna community structure and distribution of Watu Joglo cave area, Gunung Kidul, Special Region of Yogyakarta
Authors: Ayu Khadija Lung , Maghfiroh Nishfi Laila , Falah Afghan Azka , Haekal Muhammad , Saputro Alfonsus Toribio Eko , Yudha Donan Satria
Published: April 2020

Watu Joglo is one of the caves located in the row of the Sewu mountains, Gunung Kidul, Special Regency of Yogyakarta. Watu Joglo has various suitable microhabitats for herpetofauna. So far, the study about herpetofauna’s community structure and distribution has not been carried out in Watu Joglo. This study aimed to study and map the diversity, richness, evenness, and distribution of herpetofauna in Watu Joglo. Herpetofauna’s data sampling was carried out for three days. The study was conducted on 6-8 April 2018. The data of herpetofauna community were analyzed with Shannon-Wiener diversity index, Margalef richness index, and Pielou Evenness Index. The data of herpetofauna distribution were mapped and analyzed with Avenza and ArcGis. Based on the research conducted, we found 11 species of herpetofauna which consisted of five species from Ordo Anura, four species from Subordo Lacertilia, and two species from Subordo Serpentes. Herpetofauna in Watu Joglo was widely distributed around the river. According to diversity analysis, Watu Joglo has moderate diversity index, 1.667. Besides, Watu Joglo has high evenness index which is 0.85 but low richness index which is 2.83.
A tumor growth model of Hele-Shaw type as a gradient flow
Authors: Di Marino Simone , Chizat Lénaïc
Published: April 2020

In this paper, we characterize a degenerate PDE as the gradient flow in the space of nonnegative measures endowed with an optimaltransport-growthmetric. The PDE of concern, of Hele-Shaw type, was introduced by Perthameet. al. as a mechanical model for tumor growth and the metric was introduced recently in several articles as the analogue of the Wasserstein metric for nonnegative measures. We show existence of solutions usingminimizing movementsand show uniqueness of solutions on convex domains by proving theEvolutional Variational Inequality. Our analysis does not require any regularity assumption on the initial condition. We also derive a numerical scheme based on the discretization of the gradient flow and the idea of entropic regularization. We assess the convergence of the scheme on explicit solutions. In doing this analysis, we prove several new properties of the optimal transport-growth metric, which generally have a known counterpart for the Wasserstein metric.
On stability of linear dynamic systems with hysteresis feedback
Authors: Ruderman Michael
Published: April 2020

The stability of linear dynamic systems with hysteresis in feedback is considered. While the absolute stability for memoryless nonlinearities (known as Lure’s problem) can be proved by the well-known circle criterion, the multivalued rate-independent hysteresis poses significant challenges for feedback systems, especially for proof of convergence to an equilibrium state correspondingly set. The dissipative behavior of clockwise input-output hysteresis is considered with two boundary cases of energy losses at reversal cycles. For upper boundary cases of maximal (parallelogram shape) hysteresis loop, an equivalent transformation of the closed-loop system is provided. This allows for the application of the circle criterion of absolute stability. Invariant sets as a consequence of hysteresis are discussed. Several numerical examples are demonstrated, including a feedback-controlled double-mass harmonic oscillator with hysteresis and one stable and one unstable poles configuration.
An overview of randomized controlled trials on endovascular treatment for chronic cerebrospinal venous insufficiency in multiple sclerosis patients
Authors: Simka Marian
Published: April 2020

About ten years ago it was hoped that venous angioplasty for abnormal veins, primarily the internal jugular veins, will be a much awaited treatment for multiple sclerosis. Yet, a majority of randomized clinical trials on endovascular treatment for chronic cerebrospinal venous insufficiency did not reveal clinical efficacy of these procedures in multiple sclerosis patients. Still, a detailed analysis of these trials suggests that they were poorly designed, underpowered and endovascular techniques used were often far from being optimal. Nonetheless, even considering weak points of these trials, it can be concluded that venous angioplasty should not be used as a routine treatment modality in multiple sclerosis patients. Still, a possibility that some patients may benefit from endovascular treatment cannot be ruled out. This may concern patients at early stage of the disease and presenting with lesions that can easily be managed with balloon angioplasty. Therefore, we need more studies evaluating clinical efficacy of venous angioplasty in selected subgroups of multiple sclerosis patients. Importantly, it has already been demonstrated that venous angioplasty in multiple sclerosis patients is a safe procedure. Thus, also from an ethical point of view, such trials seem justifiable.
Geburtshilfliche Anästhesie während der SARS-CoV-2-Pandemie: Übersicht der Handlungsempfehlungen
Authors: Kranke Peter , Weibel Stephanie , Sitter Magdalena , Meybohm Patrick , Girard Thierry
Published: April 2020

Die häufigsten menschlichen Coronaviren verursachen unkomplizierte Erkältungen. Drei dieser Viren jedoch lösen schwerere, akute Krankheiten aus: das Middle East Respiratory Syndrome (MERS) durch MERS-CoV, das schwere akute respiratorische Syndrom (SARS) durch SARS-CoV und COVID-19 durch SARS-CoV-2. Seitens der WHO wurde der aktuell währende Ausbruch als „global public health emergency“ eingestuft. Trotz aller Bestrebungen, das OP-Programm zu reduzieren und nicht zeitkritische operative Eingriffe zunächst abzusagen bzw. zu verschieben, sind weiter operative Eingriffe und anästhesiologische Interventionen jenseits der Intensivversorgung notwendig. Dies trifft im besonderen Maße für geburtshilfliche Eingriffe und die neuraxiale Analgesie im Rahmen des Spontanpartus zu. So wird der Kreißsaal mutmaßlich unverändert frequentiert werden und auch „elektive Sectiones“ werden weiterhin stattfinden müssen. Mittlerweile sind klinischer Verlauf und Outcome einiger COVID-19-Patientinnen mit bestehender Schwangerschaft bzw. peripartale Verläufe berichtet worden. Es liegen bereits zahlreiche Empfehlungen nationaler und internationaler Gremien in Bezug auf die Versorgung solcher Patientinnen vor. Einige dieser Empfehlungen sollen im Rahmen dieses Beitrages kursorisch dargelegt werden. Die Auswahl der Aspekte soll keineswegs als eine Form der Priorisierung angesehen werden. Die allgemeinen Behandlungsgrundsätze im Umgang mit COVID-19-Patientinnen und die Handlungsempfehlungen zur intensivmedizinischen Therapie behalten dabei auch für schwangere und postpartale Patientinnen Gültigkeit. Insofern ergeben sich naturgemäß erhebliche Redundanzen, und nur wenige Aspekte treffen streng bzw. ausschließlich auf das Kollektiv geburtshilflicher Patientinnen zu. Zusammenfassend muss zum gegenwärtigen Zeitpunkt konstatiert werden, dass in der geburtshilflichen Anästhesie zunächst die allgemeinen Versorgungsempfehlungen gelten, die auch für Non-COVID-19-Patientinnen geltengültig sind. Gleichwohl ergeben sich durch die besonderen Vorgaben seitens der Hygiene bzw. des Infektionsschutzes besondere Umstände, die bei der Versorgung schwangerer Patientinnen berücksichtigt werden sollten. Diese betreffen neben medizinischen Fragen im Besonderen auch Fragen der Logistik in Hinblick auf eine räumliche Separierung, die Personalvorhaltung und materielle Ressourcen.
SARS-CoV-2/COVID-19: Empfehlungen zu Diagnostik und Therapie
Authors: Bein Berthold , Bachmann Martin , Huggett Susanne , Wegermann Petra
Published: April 2020

Der Übersichtsartikel ist als praktische Handreichung für alle gedacht, die COVID-19-Patienten behandeln bzw. in nächster Zeit behandeln werden, und fasst das derzeit verfügbare Wissen zu Diagnostik und Therapie zusammen. Zusätzlich werden auch neue und experimentelle Therapien bewertet, soweit dazu zumindest Einzelfallberichte vorliegen.
Value, Strengths, and Challenges of e-Learning Modules Paired with the Flipped Classroom for Graduate Medical Education: A Survey from the National Neonatology Curriculum
Authors: Gray Megan M. , Dadiz Rita , Izatt Susan , Gillam-Krakauer Maria , Carbajal Melissa M. , Falck Alison J. , Bonachea Elizabeth M. , Johnston Lindsay C. , Karpen Heidi , Vasquez Margarita M. , Chess Patricia R. , French Heather
Published: April 2020

Objective This study aimed to determine the value, strengths, and challenges of implementing an e-learning based flipped classroom (FC) educational modality as part of the standardized physiology National Neonatology Curriculum (NNC), created for neonatal-perinatal medicine (NPM) fellow learners and faculty educators.

Study Design This is a cross-sectional study of NPM fellows and faculty educators who utilized at least one of the e-learning based NNC FC respiratory physiology programs between May and September 2018. Participants were surveyed anonymously regarding their experiences participating in the NNC, including measures of preparation time. A combination of descriptive statistics and proportion comparisons were used for data analysis.

Results Among 172 respondents, the majority of fellow and faculty respondents reported positive attitudes toward the educational content and case discussions, and the majority supported national standardization of NPM physiology education (92%). Fellows reported greater preclass preparation for their FC compared with previous didactic lectures (30–60 vs. 0–15 minutes, p < 0.01). Faculty facilitators reported less preparation time before facilitating a FC compared with the time required for creating a new didactic lecture (median: 60 vs. 240 minutes, p < 0.01). Both fellows and faculty respondents preferred the FC approach to traditional didactics, with fellows showing a greater degree of preference than faculty (68 vs. 52%, respectively, p = 0.04).

Conclusion Fellows and faculty educators supported the FC learning, reporting peer-to-peer learning, and the establishment of a learning community which promotes adult learning and critical thinking skills. A national physiology curriculum creates equitable and engaging educational experiences for all NPM fellows while reducing individual program burden of content creation. Our findings further supported the development of an NNC using a flipped classroom modality.
Protecting Labor and Delivery Personnel from COVID-19 during the Second Stage of Labor
Authors: Palatnik Anna , McIntosh Jennifer J.
Published: April 2020

The novel coronavirus disease 2019 (COVID-19) is spreading fast and is affecting the clinical workers at much higher risk than the general population. Little is known about COVID-19 effect on pregnant women; however, the emerging evidence suggests they may be at high risk of asymptomatic disease. In light of projected shortage of personal protective equipment (PPE), there is an aggressive attempt at conservation. In obstetrics, the guidelines on PPE use are controversial and differ among hospitals, globally, as well as nationally. The centers for disease control and prevention (CDC) recommend using N95 respirators, which are respirators that offer a higher level of protection instead of a facemask for when performing or present for an aerosol-generating procedures (AGP). However, the second stage of labor is not considered an AGP. The second stage of labor can last up to 4 hours. During that time, labor and delivery personnel is in close contact to patients, who are exerting extreme effort during and frequently blow out their breath, cough, shout, and vomit, all of which put the health care team at risk, considering that COVID-19 transmission occurs through aerosol generated by coughing and sneezing. The CDC and the American College of Obstetricians and Gynecologists (ACOG) do not provide clarification on the use of N95 during the second stage. We recommend that labor and delivery personnel have the utmost caution and be granted the protection they need to protect themselves and other patients. This includes providing labor and delivery personnel full PPE including N95 for the second stage of labor. This is critical to ensure the adequate protection for health care workers and to prevent spread to other health care workers and patients.

Key Points
Investigations of the effects and mechanisms of metal interconnection layer of AlN-based complementary resistive switches
Authors: Hung Pei-Hao , Li Cheng-Ying , Min Kao-Peng , Lin Chun-Cheng , Chu Sheng-Yuan
Published: April 2020

Complementary resistive switches (CRSs) are currently considered to be the best solution for sneak current generated in circuits in crossbar passive arrays due to their high resistance at low voltages. However, their endurance is currently the greatest challenge (<100 times). Therefore, how to improve the devices’ endurance will be an important issue. In this study, we investigate the metal interconnection layer (Ti, Cu, and Ag) of AlN-based CRSs, and we find that the devices that used Ag as the interconnection layer effectively increased endurance up to 500 times and have the lowest operating voltage. This study concludes that this is related to the diffusion of metal into the insulating layer.
The role of rotation–vibration coupling in symmetric and asymmetric isotopomers of ozone
Authors: Gayday Igor , Teplukhin Alexander , Kendrick Brian K. , Babikov Dmitri
Published: April 2020

A theoretical framework and a computer code (SpectrumSDT) are developed for accurate calculations of coupled rotational–vibrational states in triatomic molecules using hyper-spherical coordinates and taking into account the Coriolis coupling effect. Concise final formulas are derived for the construction of the Hamiltonian matrix using an efficient combination of the variational basis representation and discrete variable representation methods with locally optimized basis sets and grids. First, the new code is tested by comparing its results with those of the APH3D program of Kendrick et al. [Kendrick, Pack, Walker, and Hayes, J. Chem. Phys. 110, 6673 (1999)]. Then, accurate calculations of the rovibrational spectra are carried out for doubly substituted symmetric (18O16O18O) and asymmetric (18O18O16O) ozone isotopomers for the total angular momentum up to J = 5. Together with similar data recently reported for the singly substituted symmetric (16O18O16O) and asymmetric (16O16O18O) ozone isotopomers, these calculations quantify the role of the Coriolis coupling effect in the large mass-independent isotopic enrichment of ozone, observed in both laboratory experiments and the atmosphere of the Earth. It is found that the Coriolis effect in ozone is relatively small, as evidenced by deviations of its rotational constants from the symmetric-top-rotor behavior, magnitudes of parity splittings (Λ-doubling), and ratios of rovibrational partition functions for asymmetric vs symmetric ozone molecules. It is concluded that all of these characteristics are influenced by the isotopic masses as much as they are influenced by the overall symmetry of the molecule. It is therefore unlikely that the Coriolis coupling effect could be responsible for symmetry-driven mass-independent fractionation of oxygen isotopes in ozone.
Comparison between x-ray diffraction and quantitative surface calorimetry based on infrared thermography to evaluate strain-induced crystallinity in natural rubber
Authors: Le Cam J.-B. , Albouy P.-A. , Charlès S.
Published: April 2020

The crystallinity of stretched crystallizable rubbers is classically evaluated using x-ray diffraction (XRD). As crystallization is a strongly exothermal phenomenon, quantitative surface calorimetry from infrared thermography offers an interesting alternative to XRD for determining the crystallinity. In this paper, the two measurement techniques have been used for evaluating the strain-induced crystallinity of the same unfilled natural rubber. This study provides the first comparison between the two techniques. The results obtained highlight the very satisfactory agreement between the two measurements, which opens a simple way for evaluating the strain-induced crystallinity from temperature measurements.
Turbulent drag induced by low surface roughness at transonic speeds: Experimental/numerical comparisons
Authors: Hue David , Molton Pascal
Published: April 2020

This paper gives the main results of an experimental test campaign aimed at quantifying the effects of very low roughness levels on the flat plate turbulent drag in transonic conditions. This work, in a field not completely understood yet, the one of the transitionally rough regime, has revealed its importance by showing that some surfaces considered as hydrodynamically smooth in past studies might not have been. This issue can be strongly critical in the delicate exercise of experimental/numerical comparisons, and more specifically, when it comes to absolute drag predictions, if the fluid dynamics computations use only, as they almost always do, infinitely smooth surfaces. The experiments on the S8Ch wind tunnel have involved high-level measurement techniques, such as micro-drag evaluation with a three-component balance and near-wall laser Doppler velocimetry, for Mach numbers from 0.55 to 0.8 and maximum Reynolds numbers based on the sample length and the boundary layer thickness of about 2.6 × 106 and 0.13 × 106, respectively, the highest friction Reynolds number being close to 5000. A dozen surface samples were tested, with average roughness values from less than 0.25 μm (mirror-polished aluminum) to more than 10 μm (commercial sandpapers), and in between standard-machined or painted samples (including pressure sensitive paintings). A pragmatic computational fluid dynamics study reproducing this test campaign was completed. It is based on the well-known equivalent sand grain roughness height approach and also on the Musker correlation, which was adapted. The results and validity of such Reynolds-averaged Navier–Stokes simulations in that particular regime are discussed. Anyway, both experimental and numerical outcomes of this work are in agreement to indicate that drag can be significantly impacted even for roughness Reynolds numbers potentially below the usual threshold values often considered in the engineering world (i.e., about 3.5–5). And the cross-analysis of surface drag production and roughness characteristics has allowed the decisive role played by the rms (or average) roughness height, the skewness and kurtosis coefficients, and especially the slope parameter to be confirmed.
Support work function as a descriptor and predictor for the charge and morphology of deposited Au nanoparticles
Authors: Ghosh Sukanya , Mammen Nisha , Narasimhan Shobhana
Published: April 2020

We show, using density functional theory calculations, that the charge, magnetic moment, and morphology of deposited Au nanoclusters can be tuned widely by doping the oxide support with aliovalent cations and anions. As model systems, we have considered Aun (n = 1, 2, or 20) deposited on doped MgO and MgO/Mo supports. The supports have been substitutionally doped with varying concentrations θ of F, Al, N, Na, or Li. At θ = 2.78%, by varying the dopant species, we are able to tune the charge of the Au monomer between −0.84e and +0.21e, the Au dimer between −0.87e and −0.16e, and, most interestingly, Au20 between −3.97e and +0.49e. These ranges can be further extended by varying θ. These changes in charge are correlated with changes in adsorption and/or cluster geometry and magnetic moment. We find that the work function Φ of the bare support is a good predictor and descriptor of both the geometry and charge of the deposited Au cluster; it can, therefore, be used to quickly estimate which dopant species and concentration can result in a desired cluster morphology and charge state. This is of interest as these parameters are known to significantly impact cluster reactivity, with positively or negatively charged clusters being preferred as catalysts for different chemical reactions. It is particularly noteworthy that the Na-doped and Li-doped supports succeed in making Au20 positively charged, given the high electronegativity of Au.
Mapping for nonlinear electron interaction with whistler-mode waves
Authors: Artemyev A. V. , Neishtadt A. I. , Vasiliev A. A.
Published: April 2020

The resonant interaction of relativistic electrons and whistler-mode waves is an important mechanism of electron acceleration and scattering in the Earth radiation belts and other space plasma systems. For low amplitude waves, such an interaction is well described by the quasi-linear diffusion theory, whereas nonlinear resonant effects induced by high-amplitude waves are mostly investigated (analytically and numerically) using the test particle approach. In this paper, we develop a mapping technique for the description of this nonlinear resonant interaction. Using the Hamiltonian theory for resonant systems, we derive the main characteristics of electron transport in the phase space and combine these characteristics to construct the map. This map can be considered as a generalization of the classical Chirikov map for systems with nondiffusive particle transport and allows us to model the long-term evolution of the electron distribution function.
High-numerical-aperture and long-working-distance objective for single-atom experiments
Authors: Li Shaokang , Li Gang , Wu Wei , Fan Qing , Tian Yali , Yang Pengfei , Zhang Pengfei , Zhang Tiancai
Published: April 2020

We present a long-working-distance objective lens with numerical apertures NA = 0.4 for single-atom experiments. The objective lens is assembled entirely by the commercial on-catalog Φ1″ singlets. The objective can correct the spherical aberrations due to the standard flat vacuum glass windows with various thicknesses. The typical working distance is 18.2 mm at the design wavelength of 852 nm with a 5-mm thick silica window. In addition, the objective can also be optimized to work at the diffraction limit at a single wavelength in the entire visible and near infrared regions by slightly tuning the distance between the first two lenses. The diffraction limited field of view is 0.61 mm, and the spatial resolution is 1.3 μm at the design wavelength. The performances are simulated by using the commercial ray-tracing software and confirmed by imaging the resolution chart and a 1.18 μm pinhole. The objective can be used for trapping and manipulating single atoms of various species.
Spin–orbit coupling and vibronic transitions of Ce(C3H4) and Ce(C3H6) formed by the Ce reaction with propene: Mass-analyzed threshold ionization and relativistic quantum computation
Authors: Zhang Yuchen , Yang Dong-Sheng
Published: April 2020

A Ce atom reaction with propene is carried out in a pulsed laser vaporization molecule beam source. Several Ce–hydrocarbon species formed by the C—H and C—C bond activation of propene are observed by time-of-flight mass spectrometry, and Ce(C3Hn) (n = 4 and 6) are characterized by mass-analyzed threshold ionization (MATI) spectroscopy and density functional theory, multiconfiguration, and relativistic quantum chemical calculations. The MATI spectrum of each species consists of two vibronic band systems, each with several vibronic bands. Ce(C3H6) is identified as an inserted species with Ce inserting into an allylic C—H bond of propene and Ce(C3H4) as a metallocycle through 1,2-vinylic dehydrogenation. Both species have a Cs structure with the Ce 4f16s1 ground valence electron configuration in the neutral molecule and the Ce 4f1 configuration in the singly charged ion. The two vibronic band systems observed for each species are attributed to the ionization of two pairs of the lowest spin–orbit coupled states with each pair being nearly degenerate.
Magnetic enhancement of ferroelectric polarization in a particulate multiferroic composite derived in situ via additive assisted sintering of a pseudo ternary alloy system BiFeO3–PbTiO3–DyFeO3
Authors: Saha Sujoy , Singh Ram Prakash , Kumar Avinash , De Arnab , Pandey Prafull , Narayan Bastola , Basumatary Himalay , Senyshyn Anatoliy , Ranjan Rajeev
Published: April 2020

We report here the synthesis of a self-grown 0–3 particulate multiferroic composite by controlled precipitation of the ferrimagnetic garnet phase using additive (MnO2) assisted sintering of a multi-cation ferroelectric system (Bi, Pb, Dy)(Fe, Ti)O3. The particulate multiferroic composite derived in this manner exhibits a favorable microstructure, wherein, although the volume fraction of the garnet phase is kept low (6%), which helps in retaining the electrical insulating character of the specimen, the number fraction of the garnet grains vis-à-vis the ferroelectric grains is ∼1:1. The composite shows a nearly ∼50% increase in saturation polarization at room temperature under a modest magnetic field of 1 T, suggesting a considerable improvement in ferroelectric domain switching due to the efficient strain transfer from the minority garnet grains to the majority piezoelectric grains.
Optical properties of cubic boron arsenide
Authors: Song Bai , Chen Ke , Bushick Kyle , Mengle Kelsey A. , Tian Fei , Gamage Geethal Amila Gamage Udalamatta , Ren Zhifeng , Kioupakis Emmanouil , Chen Gang
Published: April 2020

The ultrahigh thermal conductivity of cubic boron arsenide (BAs) makes it a promising material for next-generation electronics and optoelectronics. Here, we report measured optical properties of BAs crystals, including the complex dielectric function, refractive index, and absorption coefficient in the ultraviolet, visible, and near-infrared wavelength range. The data were collected at room temperature using spectroscopic ellipsometry and transmission and reflection spectroscopy. We further calculated the optical response using density functional theory and many-body perturbation theory, considering quasiparticle and excitonic corrections. The computed values for the direct and indirect bandgaps (4.25 eV and 2.07 eV) agree well with the measured results (4.12 eV and 2.02 eV). Our findings pave the way for using BAs in future electronic and optoelectronic applications that take advantage of its demonstrated ultrahigh thermal conductivity and predicted high ambipolar carrier mobility.
Effect of sheath thickness on the propagation constant of electromagnetic waves propagating along thin plasma layer coated metallic surface
Authors: Li Wenqiu , Zhao Bin , Wang Gang , Xiang Dong
Published: April 2020

Solving or mitigating the blackout problem suffered by hypersonic vehicles as they re-enter the atmosphere is essential for the smooth communication of hypersonic vehicles. An antenna–sheath–plasma layer configuration is proposed, whose analytical results indicate that the attenuation of the wave mode can be reduced significantly through optimizing the sheath thickness between the hypersonic vehicle antenna and the surrounding plasma layer. Detailed investigations show that because the wave frequency is greater than the plasma frequency, i.e., ωpe < ω, there exists great influence of the sheath thickness parameter δ on the propagation constant for the m = 1, 2, 3 modes as δ ∈ (0.01, 1) and for the m = 0 mode as δ > 1; for the ωpe > ω case, δ imposes a significant effect on the propagation constant for the m = 0, 2, 3 modes as δ ∈ (0.1, 2) and for the m = 1 mode as δ < 1; in addition, it shows that the attenuation constant for the m = 1 mode is always non-zero, which implies that the blackout problem is mainly caused by the m = 1 mode when ωpe > ω.
Multifunctional composites for elastic and electromagnetic wave propagation
Authors: Kim Jaeuk , Torquato Salvatore
Published: April 2020

Significance

We establish accurate microstructure-dependent cross-property relations for composite materials that link effective elastic and electromagnetic wave characteristics to one another, including effective wave speeds and attenuation coefficients. Our microstructure-dependent formulas enable us to explore the multifunctional wave characteristics of a broad class of disordered microstructures, including exotic disordered “hyperuniform” varieties, that can have advantages over crystalline ones, such as nearly optimal, direction-independent properties and robustness against defects. Applications include filters that transmit or absorb elastic or electromagnetic waves “isotropically” for a range of wavelengths. Our findings enable one to design multifunctional composites via inverse techniques, including the exterior components of spacecraft or building materials, heat sinks for CPUs, sound-absorbing housings for motors, and nondestructive evaluation of materials.
Media political parallelism and political agenda setting in Italy
Authors: Seddone Antonella
Published: April 2020

The issue of whether and how political parallelism could play a role in the agendadynamics between media and politics is relevant. Yet, this issue has been exploredonly rarely and the findings are unclear. Using Italy as an illustration, this studyinvestigates the interactions between parallel media and the political agenda between2006 and 2011. Based on the analysis of a longitudinal dataset, this investigation aimsto assess whether and to what extent parallel media coverage may have affected thepolitical agenda concerning two policy issues: (i) reform of the labor market and (ii) theaccess of regular migrants to Italian citizenship. Specifically, the media’s attention tothese two policy issues will be analyzed based on the parliamentary questions (PQs)addressed by members of Parliament (MPs).
The impact of simultaneous-interpreting prosody on comprehension
Authors: Lenglet Cédric , Michaux Christine
Published: April 2020

Does the particular prosody of simultaneous interpreting have an impact on comprehensibility? This paper presents an experiment that sought to answer this question. Two groups of listeners (47 with relevant contextual knowledge about the subject-matter of the speech and 40 with less contextual knowledge) listened to the interpretation into French of a 20-minute lecture in German under two conditions (the actual interpretation and a read-aloud rendition of the transcript of the interpretation by the same interpreter) and answered comprehension questions. The prosodic features of the two conditions were analysed, and differences regarding the temporal organisation of speech, disfluencies, pitch register and the interface between prosody and syntax emerged. Simultaneous interpreting was found to be more monotonous, to contain a larger number of short and long silent pauses, more hesitations (“euh”) and more non-syntactic pauses as well as to have a more irregular speech rate. The read-aloud version was livelier, with more medium-length silent pauses and almost no hesitation. Results of the comprehension questionnaire do not demonstrate that interpreting-specific prosodic features affect comprehensibility to a significant extent. This is consistent with professional norms of interpreting in specialised conferences, where verbal aspects have priority over non-verbal ones.
The role of verbal working memory in L2 sentence comprehension
Authors: Kerz Elma , Wiechmann Daniel
Published: April 2020

Considerable variability has been observed in sentence comprehension abilities in both native speakers and second language (L2) learner populations. While it has long been established that, in native speakers, this variability is closely linked to individual differences (IDs) in verbal working memory (vWM), previous research on the role of vWM in L2 sentence comprehension has produced mixed results. Moreover, there is an accumulating body of evidence demonstrating that the relationship between vWM and native language comprehension abilities is mediated by language experience. However, to our knowledge, until now, no attempt has been made to integrate language experience measures into the vWM-L2 sentence comprehension relationship. The goal of the present study is twofold: (1) to determine whether and to what extent vWM – as gauged by a reading span (RSPAN) task – correlates with IDs in two proxy estimates of L2 experience and (2) to investigate the effects of vWM on L2 comprehension of three different types of complex sentences. Thirty-four German advanced learners of English participated in this study. Significant positive correlations were found between the RSPAN scores and both proxy estimates of L2 experience. Mixed-effects modeling revealed that vWM exerted a significant effect on L2 sentence comprehension that was not modulated by sentence type. Taken together, these results provide additional evidence in support of the involvement of vWM in L2 sentence comprehension and, to our knowledge, first evidence for the contribution of L2 experience to RSPAN task performance.
Evidentiality and humor in Spanish
Authors: Ruiz-Gurillo Leonor
Published: April 2020

The aim of this paper is to shed light on the evidentiality functions used by the comedian Andreu Buenafuente during his monologues in Spanish (2007–2011). Firstly, some hypotheses are proposed: (1) genre may determine pragmatic evidentiality functions; (2) evidentials are integrated into a monologue’s expository-argumentative structure; (3) several evidentiality strategies may be distinguished with regard to this structural role; (4) one of these strategies in humorous texts consists of acting as a humorous evidentiality marker. Secondly, reportative evidentials (Willet, 1988;Plungian 2001;Dendale & Tasmowski, 2001, p. 343) such assegún, según dicen, dicen que(‘[they/people]) say’) andse ve que(lit. ‘it is seen that/apparently’), and a direct attested evidential,claro(‘of course’), are analyzed. Both quantitative and qualitative analyses serve as the basis to confirm the hypotheses posed and finally to propose a semantic-pragmatic framework for evidentials and evidentialty in Andreu Buenafuente’s humorous monologues. The corpus comprises 203 printed monologues from the booksSigo diciendo(‘I still say’) (2009),Digo yo(‘So I say’) (2010) andHablar es gratis(‘Speaking is free of charge’) (2011).
Comunicar emociones en Facebook
Authors: Fernández-Vallejo Ana M.
Published: April 2020

La comunicación entre empresa y cliente ha cambiado con la irrupción de las redes sociales en la comunicación corporativa: la comunicación bidireccional (empresa a cliente) se ha transformado en multidireccional (cliente a cliente o cliente a empresa) y el elemento emocional ha entrado a formar parte de ese mensaje. Este estudio analiza cómo se comunican las emociones en las redes sociales de las organizaciones. El objetivo es descubrir qué estrategias multimodales de evaluación, intensificación o aproximación describen o evocan las emociones. El análisis, metodológicamente cuantitativo, está basado en un corpus conformado por un total de 3128 publicaciones (41287 palabras); estas entradas se recogieron de forma manual en el último trimestre de 2016 de la cuenta de Facebook del grupo Dia y se organizaron en tres subcorpus: posts publicados por la empresa, comentarios de la empresa y comentarios de los seguidores. Los resultados permiten extraer las siguientes conclusiones: (1) la alta frecuencia de posts con contenido emocional en la comunicación digital de las empresas, especialmente a través de redes como Facebook; (2) la prevalencia de las emociones positivas en los tres subcorpus; (3) la homogeneidad en el uso de recursos verbales y no verbales de estrategias de evaluación, intensidad y aproximación en los tres subcorpus; excepción hecha de los recursos icono-gráficos de intensidad, que es más libre en los comentarios de los seguidores.
The language of recovery
Authors: Cabrejas-Peñuelas Ana Belén
Published: April 2020

The present study attempts to make a comparative analysis of two Spanish and American political speeches, which belong to two different debate traditions, in terms of the metaphors used. For that purpose, we analyze the Economy sections of the 2015 State of the Union Address in the US and in the 2015 State of the Nation Debate in Spain. The present study aims at answering the following research questions:

What metaphors do President Obama and Prime Minister Rajoy use in the American and Spanish political speeches to convince their audiences of America’s and Spain’s economic victory?

What are the similarities and differences between the representations depicted by metaphor use in the speeches as the politicians attempt to shape the economic recovery of America and Spain after recession?

To answer these questions, we use an analytical framework for the identification of conceptual metaphors and a theoretical framework for the use of conceptual metaphors (Lakoff & Johnson, 1980). The results indicate that both politicians use metaphors in an attempt to reify the new economy in such a way that the economic policies used to fight crisis are justified, while the negative effects on citizens are not mentioned and, thus, are dismissed as unimportant. However, the politicians take different approaches to reification.