bluuebunny/crossref_metadata_2025 huggingface dataset:
Powered wind tunnel tests setup of the IRON innovative turboprop aircraft
Authors: Ciliberti Danilo , Cusati Vincenzo , Della Vecchia Pierluigi , Corcione Salvatore , Nicolosi Fabrizio
Published: December 2019

This paper describes the powered wind tunnel tests setup of the innovative configuration of the IRON regional turboprop aircraft. The objective of the tests is the evaluation of propulsive effects on aircraft stability and control characteristics. During the setup process, several aerodynamic issues have been anticipated and here illustrated. A scaled engine deck has been derived from the full-scale data provided by the IRON powerplant consortium partner. From two representative flight conditions, the characteristics of the scaled motor as RPM, torque and power have been calculated, providing a choice for the electric motors to install in the test section. The motors’ operating voltage and current determined the sizing of the power, acquisition and control system. Similarly, the desired propeller coefficients were the target of a propeller design process, which was performed with XROTOR, MATLAB®, XFOIL and validated with RANS analyses. Finally, to directly evaluate the propeller thrust and normal force, motors’ supporting structures with load cells have been conceptually designed.
F100-PW-229 Engine Fault Detection Based on Real Time Data
Authors: Kolios Vasileios , Templalexis Ioannis , Lionis Ioannis , Antonogiannakis Emmanouil , Kotsiopoulos Petros
Published: December 2019

Gas turbine engines exhibit very high maintenance costs. Moreover, in the case of aero applications an in-flight engine incidence, shall, by all means, be avoided, a condition that drives total maintenance costs even higher. A measure in favor of balancing these costs is to monitor continuously the variation of engine performance data recorded during flight, establish methods to deduce useful information regarding the engine “health” status and, as a result, take appropriate actions to maintain a good engine operating condition. The current work presents such a method tailored on the “F100-PW-229” engine that is operated by the ellenic Air Force as the propulsion system of the “F-16 block 52M” aircraft [3]. CEDATS and MS Excel were the computational tools used for the current engine performance study. CEDATS is a software developed for the engine users. It provides basic data trend monitoring functions and engine fault warnings. It is well known that there is always space for improvement for such health monitoring tools since there are cases where engine operating faults are not captured. Within the frame of the current work, a data post – processing method on the engine performance data time series was applied using MS Excel, in order to raise early warnings of an uncaptured compressor operating fault.
An Application of the ECMS Strategy to a Wankel Hybrid Electric UAV
Authors: Donateo Teresa , De Pascalis Claudia Lucia , Ficarella Antonio
Published: December 2019

In a previous work, the authors optimized the hybrid electric power system for a tactical Unmanned Aerial Vehicle including a Wankel engine as thermal converter and a permanent magnet electric motor powered by lithium batteries. Startingfrom this optimal configuration, we address here the topic of a refined optimization of the energy management strategy, i.e. the contribution of the battery to the required power in each segment of the flight. The Equivalent Consumption Minimization Strategy (ECMS) was chosen with the goal of minimizing fuel consumption while fully depleting the energy stored in the battery from the beginning to the end of each mission.
Electric motor-glider powered by a hydrogen fuel cell stack
Authors: Czarnocki Piotr , Dudek Magdalena , Drabarek Krzysztof , Frączek Wojciech , Iwański Grzegorz , Miazga Tomasz , Nikoniuk Marcin , Raźniak Andrzej , Rosół Maciej
Published: December 2019

The paper presents the current development of the AOS-H2 electric motor-glider project. The project encompasses the design and manufacture of an electric propulsion system (EPS) and a CF/epoxy airframe to be used as a flying test platform for the designed EPS. A 40-kW electric motor is supplied by a 10-kW PEM fuel cell stack and a Li-ion battery during run-up and ascent and by the fuel cell stack alone during steady flight. The airframe and the EPS have been completed; the results of bench tests of the EPS have proved that it meets the established requirements..
Preliminary analysis on an IVHM approach for prognosis of high-pressure filters for hydraulic Power Control Modules of helicopters
Authors: De Martin Andrea , Jacazio Giovanni , Sorli Massimo , Surdo Vincenzo
Published: December 2019

The process of filtration is critical to ensure long operative life to on-board hydraulic equipment, especially in rotating-wing application where the severe vibratory environment lead to accelerated wear of the mechanical components and hence an increased production of debris. Filtration is obtained by mechanically separating the physical contaminants from the hydraulic fluid by means of filters, which hence tend to clog under prolonged usage. Filter replacement has been so far pursued through scheduled maintenance strategy, which however have proven to be rather cost-ineffective. To transition to a Condition-Based Maintenance, new Prognostics and Health Monitoring frameworks need to be developed. The paper deals with the feasibility analysis of such a system based on a high-fidelity simulation environment, rigorous description of the operating conditions and state-of-the-art algorithms.
Optimal civil aircraft missions exploiting free routing possibilities
Authors: Katsikogiannis Dimitrios , Thoma Marily , Mathioudakis Konstantinos , Aretakis Nikolaos , Alexiou Alexios
Published: December 2019

A method is presented for optimizing burnt fuel and flight time of civil aircraft missions, under the scope of a full-scale free route airspace implementation as well as usage of actual environmental data, focusing on ambient temperature and pressure. A computational analysis model, using online available aircraft data is considered, for flight envelopes defined by the user, is used as the base tool. The model is validated over real flight data, before it is used as the main tool for optimization of flight missions. Flight paths are analyzed by considering both their vertical and horizontal aspect. Optimal paths are derived, for each chosen mission, through an optimization process that takes advantage of the flexibilities that become available by implementation of Free Route Airspace. Vertical flight path is shown to play very important role in achieving optimal flights, while horizontal paths also offer optimality possibilities, with a strong dependence on weather conditions.
Flight Test of Pilot-Aircraft Haptic Feedback System
Authors: Zikmund Pavel , Dubnický Lukáš , Horpatzká Michaela , Macík Miroslav , Jebáček Ivo
Published: December 2019

This research is focused on an innovative improvement of pilot-aircraft interaction and is targeted on small aircraft. Haptic feedback is performed by actuators mounted on an aircraft's controls. The purpose of the actuators on a control stick and pedals is stall warning and a pilot guiding to safe and economical flight regimes. The feedback system mediates airflow data as angles of attack and sideslip. The paper brings results of a flight test of the proposed system. Qualitative evaluation of the haptic feedback inflight is presented. Benefits of the system are presented on a sideslip during turning. Some recommendations for the haptic pilot-aircraft interaction are stated within the discussion of the flight test results.
A reactive control system for a partially guided small sounding rocket
Authors: Constantinescu Cristian Emil
Published: December 2019

Most small sounding rockets are unguided vehicle. Stability is solved aerodynamically using fins and/or rapidly spinning the vehicle and trajectory is determined by the azimuth and elevation of the launch pad as the rocket usually fly a gravity turn. Access to upper atmosphere usually require two or three stages and the presence of fins on the upper stages inflict a penalty on the stability of the launcher in the start configuration. The paper presents a modification made to an existing launcher suggested by the need to add dead weight for stability when flying small payloads. By eliminating the fins from the second stage and using a RCS for active stability and control of the upper stage several opportunities arise: the aerodynamic configuration is simpler and the stability in the start configuration improved, drag is reduced a bit, non-gravity turn evolutions are possible and special payload requested attitudes (mainly orienting a camera towards ground) are conceivable. Of course, this require a new OBC with enhanced sensors and new navigation and flight control algorithms.
Autophagie et spermatozoïde
Authors: Buschiazzo Antoine , Yefimova Marina , Bourmeyster Nicolas , Fautrel Alain , Burel Agnès , Neyroud Anne-Sophie , Pimentel Céline , Jaillard Sylvie , Jégou Bernard , Ravel Célia
Published: December 2019

La spermiogenèse, étape ultime de la spermatogenèse, est un processus qui fait intervenir des acteurs qui participe à l’autophagie. C’est en effet lors de cette étape que se forme l’acrosome par fusion vésiculaire et que disparaît la majeure partie du cytoplasme du spermatozoïde. L’autophagie (littéralement « se manger soi-même »), en permettant l’élimination et le remplacement continuel des protéines et des organites non fonctionnels, assure le recyclage des constituants de la cellule. C’est un mécanisme cellulaire très conservé au sein des cellules eucaryotes. La machinerie de l’autophagie est également présente dans les spermatozoïdes. Elle régule la vitalité de ces cellules et leur mobilité. Les conséquences environnementales et comportementales sur l’autophagie et sur la spermatogenèse commencent à être étudiées. Le but de cette revue est de synthétiser les connaissances actuelles concernant les processus d’autophagie dans le gamète mâle mature.
Maurice Raynaud (1834–1881) und das Mysterium „Raynaud-Phänomen“
Authors: Koehler Ulrich , Portig Irene , Hildebrandt Olaf , Koehler Niklas Alexander
Published: December 2019

Maurice Raynaud first described color changes and symptoms of the fingers due to cold-induced vasospasm and restricted blood flow in his medical school thesis in 1862. Raynaud’s phenomenon is common and exists as an uncomplicated primary Raynaud phenomenon and a Raynaud phenomenon secondary to underlying diseases and medication. Mechanisms contributing to altered vasoconstrictor activity are endothelial and not-endothelial. Cold-induced vasospasm is probably a thermoregulatory problem and effects are mediated by sympathetic activity and selective stimulation of alpha2c-adrenoreceptors.
Leib- und Seelenärzte Karrieren und Komplikationen von König David bis heute
Authors: Förstl Hans
Published: December 2019

Court physicians need to deal with a clientele posing particular personality problems (e. g. rex inutilis) in a difficult environment characterized by specific health issues (morbi aulici) and they may have to avoid serious risks or want to seek great opportunities (medicus politicus). Very few have been successful as King David, a former music therapist without a medical degree, or the dentist and president Gurbanguly Berdimuhamedow. Several became victims of fatal circumstances. Not all could resist temptation of questionable literary fame at the expense of confidentiality. All told, a career close to high profile leaders needs to be considered carefully as risks may outweigh benefits.
Genetische Ursachen von Epilepsien
Authors: Wolking Stefan , Lerche Holger
Published: December 2019

Die Erkenntnisse über genetische Ursachen von Epilepsien haben in den vergangenen Jahren rasant zugenommen. Neben epileptischen Enzephalopathien stehen mittlerweile die genetischen generalisierten sowie die nicht läsionellen fokalen Epilepsien stärker im Fokus. An die genetische Ursache angepasste Behandlungswege im Sinne der ‚Precision Medicine‘ eröffnen zunehmend individualisierte Therapieoptionen. Die Pharmakogenetik könnte zudem die Vorhersage von Therapieansprechen bzw. Nebenwirkungen unterstützen und somit die Therapiesicherheit erhöhen. Genetische Diagnostik ist für eine zunehmende Anzahl von Epilepsiepatienten sinnvoll und wird weiter an Bedeutung zunehmen.
Schrecksekunde – was bedeutet diese Lücke?
Authors: Keller Frieder
Published: December 2019

Ludwig van Beethoven’s Opus 119 represents a series of “bagatelles” for piano. On closer inspection, or better listening, one can get to the thought: How should one interpret the pause that the Maestro has woven into bar 65 of the first piece?
Fetomaternal Hemorrhage: Can We Use Hemoglobin Electrophoresis as a
Diagnostic Tool?
Authors: Stanic Zana , Stanisic Lada , Fureš Rajko , Persec Zoran , Dapic Kresimir , Hrgovic Zlatko
Published: December 2019

Fetomaternal hemorrhage (FMH) is usually detected by either the Kleihauer-Betke
(KB) test or by 2 cytometry, the latter of which represents the gold standard of
FMH diagnosis today. But what do we do when neither method is available? We
present two cases of suspected FMH due to their characteristic signs and
symptoms that were ultimately confirmed by hemoglobin electrophoresis (HE).
Update on Ocular Myasthenia Gravis
Authors: O'Hare Meabh , Doughty Christopher
Published: December 2019

Myasthenia gravis is an antibody-mediated autoimmune disorder of the post-synaptic neuromuscular junction resulting in fluctuating, fatigable weakness. Most patients first present with extraocular symptoms (diplopia and/or ptosis), and in 15% of cases symptoms will remain restricted to only the extraocular muscles (ocular myasthenia gravis [OMG]). The history and clinical examination are of the utmost importance in correctly identifying OMG patients, as supportive serologic or electrodiagnostic studies are frequently nondiagnostic. In this review, we outline a diagnostic approach to OMG (focusing on key clinical features), discuss therapeutic options, and highlight recent developments in the understanding of OMG.
Role of Kisspeptin and NKB in Puberty in Nonhuman Primates: Sex Differences
Authors: Garcia James P. , Keen Kim L. , Seminara Stephanie B. , Terasawa Ei
Published: December 2019

To understand the roles of kisspeptin and neurokinin B (NKB) in puberty and sex differences in their involvement, we conducted a series of experiments measuring the release of gonadotropin-releasing hormone (GnRH) and kisspeptin in the median eminence of the hypothalamus in male and female monkeys throughout sexual development. Results indicate that kisspeptin-10 and the NKB agonist, senktide, stimulated GnRH release in males and females at the prepubertal and pubertal stages, but females are much more sensitive to kisspeptin signaling than males. Moreover, throughout the progress of puberty, major remodeling of kisspeptin and NKB signaling pathways for the regulation of GnRH release takes place. In females during puberty, reciprocal pathways (i.e., kisspeptin signaling mediated through NKB neurons and NKB signaling mediated through kisspeptin neurons) are established, to provide powerful and flexible mechanisms for GnRH neurosecretory activity necessary for complex female reproductive function in adulthood. By contrast, during puberty in males, reciprocal pathways are consolidated to a simpler kisspeptin-dominant signaling pathway. Nevertheless, in primates, both kisspeptin and NKB signaling are contributing factors for the pubertal increase in GnRH release, rather than initiating puberty.
The Role of Kisspeptin in Sexual Behavior
Authors: Hellier Vincent , Brock Olivier , Bakker Julie
Published: December 2019

Sexual behavior is essential for the perpetuation of a species. In female rodents, mate preference and lordosis behavior depend heavily on the integration of olfactory cues into the neuroendocrine brain, yet its underlying neural circuits are not well understood. We previously revealed that kisspeptin neurons in the anteroventral periventricular nucleus/periventricular nucleus continuum (AVPv/PeN) are activated by male olfactory cues in female mice. Here, we further reveal that male-directed mate preferences and lordosis are impaired in kisspeptin knockout mice but are rescued by a single injection with kisspeptin. Acute ablation of AVPV/PeN kisspeptin neurons in adult females impaired mate preference and lordosis behavior. Conversely, optogenetic activation of these neurons triggered lordosis behavior. Kisspeptin neurons act through classical GPR54/GnRH signaling in stimulating mate preferences, but unexpectedly, GPR54/GnRH neuronal ablation did not affect lordosis behavior. Therefore, to identify the downstream components of the neural circuit involved in lordosis behavior, we employed genetic transsynaptic tracing in combination with viral tract tracing from AVPV/PeN kisspeptin neurons. We observed that kisspeptin neurons are communicating with neurons expressing the neuronal form of nitric oxide synthase. These results suggest that hypothalamic nitric oxide signaling is an important mechanism downstream of kisspeptin neurons in the neural circuit governing lordosis behavior in female mice.
Correction: Escaping optimization traps: the role of cultural adaptation and cultural exaptation in facilitating open-ended cumulative dynamics
Authors: Winters James
Published: December 2019

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Low frequency and wide band gap metamaterial with divergent shaped star units: Numerical and experimental investigations
Authors: Kumar Nitish , Pal Siladitya
Published: December 2019

Accomplishing low frequency and wide bandgaps with a single phase metamaterial remains a challenging task. In this work, we propose a single phase acoustic metamaterial having periodically arranged divergent shaped star units and performed numerical simulation to obtain the bandgaps. The simulation results demonstrate that the metamaterial exhibits an uninterrupted and extended bandgap that lies in the low frequency regime. We fabricated the structure based on numerical investigations, and using the experimental technique, elastic wave transmission characteristics have been analyzed. Experimental observations are in good agreement with numerically calculated bandgaps. Moreover, we perform a parametric study on the bandgaps with geometrical parameters like the concave angle and length of divergent ribs of the unit cell.
Biogas production from chicken manure at different organic loadings using a special zeolite additive (ZeoVit sorbent)
Authors: Baltrėnas Pranas , Kolodynskij Vitalij , Urbanas Davyd
Published: December 2019

This work was aimed at investigating biogas production from chicken manure (common agricultural organic waste) using different organic loadings and a special zeolite additive (ZeoVit sorbent), by applying a small-sized batch-type bioreactor operating under mesophilic conditions (35 °C) with mechanical mixing of the substrate. The effect of the zeolite used in the amount of 10% (percent of dry organic matter) on the promotion of biogas production efficiency was investigated under different organic loadings (80, 120, and 180 g VS l−1) of the bioreactor. It was found that increasing the organic load also increased the promoting effect of the zeolite additive, for which the best results achieved were 10% and 14% for the cumulative biogas yield and total amount of methane, respectively. The obtained results show that the zeolite additive can greatly impact the biogas yield, whereas its promoting effect upon the methane concentration was much lower (4%). The methane concentration reached a maximal value of ∼70%, while the concentrations of the most important components of the cumulative produced biogas were 60%, 38%, and 0.03% for CH4, CO2, and H2S, respectively.
An integrable all-silicon slotted photonic crystal Raman laser
Authors: Pradhan Akash Kumar , Sen Mrinal
Published: December 2019

The design of an integrable all-silicon Raman laser of a foot print of ∼7 μm is proposed based on a slotted photonic crystal nanocavity. The slot has been considered to be made of a silicon nanocrystal to encash its giant Raman gain coefficient, along with the tight spatial and temporal confinement of light in the slot, exhibiting a lasing efficiency of ∼17.8% at a wavelength of 1552 nm. Simulations depict that the device requires a very small optical threshold power of the order of 0.5 μW. Tolerances to the fabrication imperfections have also been evaluated, which explores that the device performance is tolerant up to a 6% random deviation in structural parameters like radius and in-plane positions of the holes. It has also been seen through simulations that the submicrowatt threshold is maintained even for a large deterioration of over 30% in the Q-factors and modal volumes, which reassures the realization feasibility of the device.
Impact of growth conditions and strain on indium incorporation in non-polar m-plane (101¯) InGaN grown by plasma-assisted molecular beam epitaxy
Authors: Senichev Alexander , Dzuba Brandon , Nguyen Trang , Cao Yang , Capano Michael A. , Manfra Michael J. , Malis Oana
Published: December 2019

We establish the relationships between growth conditions, strain state, optical and structural properties of nonpolar m-plane (101¯0) InGaN with indium composition up to 39% grown by plasma-assisted molecular beam epitaxy. We find that indium mole fraction as a function of growth temperature can be explained by an Arrhenius dependence of InN decomposition only for high temperature and low indium composition InGaN films. For the samples following the Arrhenius behavior, we estimate the effective activation energy for InN thermal decomposition in m-plane InGaN to be about 1 eV. This value is approximately a factor of two smaller than that reported for c-plane InGaN films. At low growth temperatures, InGaN layers show less efficient indium incorporation than predicted by Arrhenius behavior. We attribute the lower than expected indium composition at low temperatures to the strain-induced compositional pulling effect. We demonstrate that at 540 °C, the increase in the InGaN layer thickness leads to a preferential strain relaxation along the a-direction and an increase in the indium composition. For the indium mole fraction up to x ∼ 0.16, 30-nm-thick m-plane InGaN layers can be coherently grown on GaN with smooth morphology and pronounced low-temperature photoluminescence indicating that the material quality is suitable for device applications.
General stationary solutions of the nonlocal nonlinear Schrödinger equation and their relevance to the PT-symmetric system
Authors: Xu Tao , Chen Yang , Li Min , Meng De-Xin
Published: December 2019

With the stationary solution assumption, we establish the connection between the nonlocal nonlinear Schrödinger (NNLS) equation and an elliptic equation. Then, we obtain the general stationary solutions and discuss the relevance of their smoothness and boundedness to some integral constants. Those solutions, which cover the known results in the literature, include the unbounded Jacobi elliptic-function and hyperbolic-function solutions, the bounded sn-, cn-, and dn-function solutions, as well as the hyperbolic soliton solutions. By the imaginary translation transformation of the NNLS equation, we also derive the complex-amplitude stationary solutions, in which all the bounded cases obey either the PT- or anti-PT-symmetric relation. In particular, the complex tanh-function solution can exhibit no spatial localization in addition to the dark- and antidark-soliton profiles, which is in sharp contrast with the common dark soliton. Considering the physical relevance to the PT-symmetric system, we show that the complex-amplitude stationary solutions can yield a wide class of complex and time-independent PT-symmetric potentials, and the symmetry breaking does not occur in the PT-symmetric linear system with the associated potentials.
Off-axis parabolic mirror relay microscope for experiments with ultra-cold matter
Authors: Hejduk Michal , Heazlewood Brianna R.
Published: December 2019

A new optical system is introduced for the imaging of Coulomb crystals held in a cryogenic ion trap where there are space limitations preventing the placement of an objective close to the fluorescing ions. The optical system features an off-axis parabolic (OAP) mirror relay microscope that will serve to acquire images of a lattice of fluorescing ions confined within an ultra-high-vacuum vessel operating at temperatures below 10 K. We report that the OAP mirror relay setup can resolve features smaller than the separation between neighboring ions in Coulomb crystals. The setup presented here consists of two 90-degree OAP mirrors arranged into a relay from which standard microscope optics deliver the image to a camera. This design allows the first element in the imaging setup—an OAP mirror—to be located as close as possible to the ion trap, achieving high resolution without the need for a direct line-of-sight to the trap center or for a view port to be located in close proximity to the ion trap. Such an arrangement would not be possible with a standard microscope objective, which is the approach commonly adopted by the field. OAP mirrors represent a novel solution for delivering polychromatic images with micrometer-scale resolution over extended distances.
Energy-dispersive X-ray diffraction system with a spiral-array structure for security inspection
Authors: Chen Yifan , Wang Xin , Song Qinghua , Yang Baolu , Xu Jie , Xiong Kai , Mu Baozhong
Published: December 2019

Energy-dispersive X-ray diffraction (EDXRD) is a promising technique for detecting drugs and explosives in security inspections. In this study, we proposed an EDXRD structure with a spiral-array of detectors that can be used for the detection of thick objects. The detectors are configured to share the same diffraction angle, and the detection area of the system is multiplied along the optical axis. Based on the spiral-array structure, an experimental system with 5 CdTe detectors was established. Experimental results demonstrate that the accurate data can be acquired at different positions within the 250-mm detection area, and the data measured by 5 detectors have a good consistency. This work may provide a new and commercial method for the detection of thick luggage in the field of security inspection.
Investigations on band commutativity at all oxide p-type NiO/n-type β-Ga2O3 heterojunction using photoelectron spectroscopy
Authors: Ghosh Sahadeb , Baral Madhusmita , Kamparath Rajiv , Singh S. D. , Ganguli Tapas
Published: December 2019

Epitaxial growth of (111) oriented NiO layers on (−201) oriented β-Ga2O3 and vice versa have been carried out to obtain an all oxide p-n heterojunction (HJ) consisting of NiO/β-Ga2O3 and β-Ga2O3/NiO interfaces, respectively. Careful investigations by minimizing the effect of differential charging phenomena during x-ray photoelectron spectroscopy measurements yield a valence band offset (VBO) value of 1.6 ± 0.2 eV for both NiO/β-Ga2O3 and β-Ga2O3/NiO HJs. Thus, the VBO value is practically independent of the growth sequence for p-type NiO/n-type β-Ga2O3 HJs and follows band commutativity. The band diagram shows a staggered (type-II) band alignment and the value of the conduction band offset is found to be small (0.3 ± 0.2 eV). Our results are useful to design optoelectronic devices based on all oxide p-type NiO/n-type β-Ga2O3 HJs.
Quantifying configuration-entropy change during plastic flow of metallic glasses
Authors: Wang L. F. , Shao J. H. , Liu Y. H. , Lan S. , Feng T. , Hu J. , Zhang T. , Sun B. A.
Published: December 2019

Based on the energy balance principle for a serrated shear event, the configuration entropy change of a plastic flow within a shear band in metallic glasses is precisely quantified. With this method, we successfully investigated the evolution of entropy change with the plastic displacement/strain. It was found that the evolution of entropy changes for various metallic glasses follows a unified linear relation. The experimental result is consistent with the thermodynamic deduction from the free volume theory, corroborating the nature of shear-induced dilation for the plastic flow of metallic glasses.
Scales of turbulence in open-channel flows with low relative submergence
Authors: Ferraro D. , Coscarella F. , Gaudio R.
Published: December 2019

The present work aims at studying the turbulence structure developed over a highly rough bed in open-channel flows (OCFs) by varying the relative submergence through the use of three sediment sizes ranging from gravels to pebbles. The second-order moments were analyzed and compared with those already observed for canonical turbulent OCFs having similar values of relative submergence. Particular attention was paid to the turbulent Reynolds stresses, and the viscous and the form-induced shear stresses in the near bed region. The violation of the Taylor hypothesis was verified through an alternative method, by comparing two time scales, namely, the large scale advection time and the eddy characteristic nonlinear time. Moreover, an analysis of the large eddies was performed with the spectral analysis. The premultiplied spectra provide a way to quantify the contribution of different eddy scales (peaks in the premultiplied spectra) and indicate wavelengths in which a significant amount of energy resides. In order to locate the normalized wavelengths associated with the peaks in the premultiplied spectra, a systematic procedure is presented.
Large magnetoelectric effect in the polar magnet Sm2BaCuO5
Authors: Zhou Guanzhong , Gong Jingwen , Li Xiang , Liu Meifeng , Li Leiyu , Wang Yu , Min Jiahua , Liu Ju , Cai Di , Liu Fei , Zheng Shuhan , Tang Yongsen , Xu Zaichun , Xie Yunlong , Yang Lun , Zeng Min , Yan Zhibo , Li Biwen , Wang Xiuzhang , Liu Jun-Ming
Published: December 2019

Polar magnets are a family of promising candidates for future magnetoelectric (ME) applications. In particular, the ME effect is recognized for its potential use in low-power electronic devices. However, searching for materials with a sufficiently strong ME effect remains the core issue. In this work, we present a systematic investigation on oxide compound Sm2BaCuO5, including the characterization on structural, magnetic, specific heat, dielectric, and pyroelectric behaviors. The intrinsic linear ME effect is revealed, and two successive antiferromagnetic phase transitions occurring at temperatures of TN1 ∼ 5 K and TN2 ∼ 23 K are found, respectively. While a magnetic field induced electric polarization emerges below TN2 and this polarization increases with the magnetic field in an almost linear manner, another weak pyroelectric current peak is detected around TN1. Furthermore, remarkable responses of both electric polarization to the magnetic field and magnetization to the electric field are demonstrated. It is suggested that the intriguing magnetic interactions play the core roles in generating the ferroelectricity and ME effect in this Sm2BaCuO5 compound.
Empirical S=O stretch vibrational frequency map
Authors: Oh Kwang-Im , Baiz Carlos R.
Published: December 2019

Dimethyl sulfoxide (DMSO) water mixtures have been widely studied due to their unique concentration-dependent bulk properties. Here, we present an empirical spectroscopic map for the sulfinyl (S=O) stretching mode. The model can be used to interpret infrared (IR) absorption and ultrafast two-dimensional infrared (2D IR) spectra and quantify hydrogen bond populations and lifetimes by directly connecting spectroscopic measurements with structures and dynamics from molecular dynamics simulations. The electrostatic map is directly parameterized against experimental absorption spectra in the S=O stretching region (980–1100 cm−1) of dilute DMSO in water. A comparison of center peak frequencies shows that the map performs well across the entire DMSO concentration range, accurately reproducing the ∼10 cm−1 red-shift per hydrogen bond observed in the experiments. We further benchmark the map by comparing experimental and simulated 2D IR spectra generated by direct numerical integration of the Schrödinger equation. We expect that this empirical frequency map will provide a quantitative platform for investigating intermolecular interactions, microscopic heterogeneity, and ultrafast dynamics in complex liquid mixtures containing DMSO.
Ultrasensitive detection of ion concentration based on photonic spin Hall effect
Authors: Liu Jiawei , Zeng Kuiming , Xu Wenhao , Chen Shizhen , Luo Hailu , Wen Shuangchun
Published: December 2019

We propose a unique application of the photonic spin Hall effect for ultrasensitive detection of the ion concentration in solution. By incorporating the quantum weak measurement, the photonic spin-Hall shift acts as the measurement pointer and the optical rotation of solution in the magnetic field acts as the postselection state. The optical rotation is related to the Faraday effect, which is sensitive to the ion concentration of the solution. The high measurement resolution with 1.4×10−4 degree for the optical rotation angle is achieved, which outperforms the standard polarimeter. Furthermore, the high resolution with 2×10−5mol/ml for the ion concentration is obtained due to the weak-value amplification in the quantum weak measurement. In our scheme, the ion concentration is real-time detected by the amplified spin-Hall shift and thereby provides possible applications in biochemical sensing and water-quality monitoring.
First principle investigation of the exposed surfaces and morphology of β-ZnMoO4
Authors: Ribeiro Renan A. P. , Oliveira Marisa C. , de Sousa Alexsandro Gama , Bomio Maurício R. D. , Motta Fabiana V. , Gracia Lourdes , de Lazaro Sergio R. , Longo Elson , Andrés Juan
Published: December 2019

Crystal shape is a critical determinant of the physical and chemical properties of crystalline materials; hence, it is the challenge of controlling the crystal morphology in a wide range of scientific and technological applications. The morphology is related to the geometry of their exposed surfaces, which can be described by their surface energies. The surface properties of β-ZnMoO4 have not yet been well explored, either experimentally or theoretically. Thus, the first-principle calculation at the density functional theory level was carried out for different low-index surfaces of β-ZnMoO4, specifically (001), (010), (110), (011), (101), and (111), and the surface energy values (Esurf) were reported. The surface stability was found to be controlled by the undercoordinated [MoOn…yVOx] and [ZnOn…yVOx] (n = 4 and 5; y = 1 and 2) clusters, i.e., their local coordination of Mo and Zn cations at the exposed surfaces, respectively, with the (111) surface being the most stable. A complete map of investigated β-ZnMoO4 morphologies was obtained using the Wulff construction and changing the values of the calculated energy surfaces. The final geometries from this map were compared with field emission-scanning electron microscopy images showing excellent agreement, prevising rectangular and hexagonal plates. Our findings will promote the use of facet engineering and might provide strategies to produce β-ZnMoO4-based materials for achieving morphology-dependent technological applications.
Fast destruction of singlet order in NMR experiments
Authors: Rodin Bogdan A. , Sheberstov Kirill F. , Kiryutin Alexey S. , Brown Lynda J. , Brown Richard C. D. , Sabba Mohamed , Levitt Malcolm H. , Yurkovskaya Alexandra V. , Ivanov Konstantin L.
Published: December 2019

Some nuclear spin systems support long-lived states, which display greatly extended relaxation times relative to the relaxation time of nuclear spin magnetization. In spin-1/2 pairs, such a long-lived state is given by singlet order, representing the difference of the population of the nuclear singlet state and the mean population of the three triplets. In many cases, the experiments with long-lived singlet order are very time-consuming because of the need to wait for singlet order decay before the experiment can be repeated; otherwise, spin order remaining from a previous measurement may lead to experimental artifacts. Here, we propose techniques for fast and efficient singlet order destruction. These methods exploit coherent singlet-triplet conversion; in some cases, multiple conversion steps are introduced. We demonstrate that singlet order destruction enables a dramatic reduction of the waiting time between consecutive experiments and suggest to use this approach in singlet-state Nuclear Magnetic Resonance (NMR) experiments with nearly equivalent spins.
Atomic-scale quantitative analysis of implanted Mg in annealed GaN layers on free-standing GaN substrates
Authors: Kumar Ashutosh , Uzuhashi Jun , Ohkubo Tadakatsu , Tanaka Ryo , Takashima Shinya , Edo Masaharu , Hono Kazuhiro
Published: December 2019

Achieving efficient p-type conduction in Mg-implanted GaN depends largely on postimplantation annealing conditions. Here, we study the effect of postimplantation annealing on the evolution of defects and their interactions with implanted Mg ions by using scanning transmission electron microscopy and atom probe tomography. We found that Mg clusters start to form by annealing the implanted sample above 1000 °C. In addition to the Mg clusters, stacking faults form at an annealing temperature of 1300 °C. The Mg concentrations of about 2–3 orders of magnitude higher than implanted Mg were segregated at the stacking faults. Nanobeam electron diffraction analysis revealed no distinct phase other than GaN formed at the Mg-enriched defects, suggesting that Mg is substituted for Ga in the GaN lattice at the edge of the stacking faults.
Spin-resolved transport physics induced by a Majorana-fermion zero mode
Authors: Niu Pengbin , Liu Lixiang , Su Xiaoqiang , Dong Lijuan , Shi Yunlong , Luo Hong-Gang
Published: December 2019

By using the Hubbard operator Green’s function method, the spin-resolved transport properties of a quantum dot coupled to metallic leads and side-coupled to a topological superconductor wire hosting Majorana bound states (MBSs) are studied theoretically. Compared with the second quantization representation, the method can lead us to an analytical result for the retarded Green’s function with finite U. The spin-related current and conductance are discussed. In the case of zero Coulomb interaction and on-resonance, the MBS’s 1/2 signature is recovered, and furthermore, there exists a 1/2 negative differential spin conductance. In the case of infinite Coulomb interaction, the 1/2 signature does not survive due to the Coulomb correlation reducing the current and conductance. Also due to this correlation, the MBS-induced symmetry of conductance peaks around zero energy is destroyed. In addition to this, we find that there are two MBS-induced negative differential spin conductance peaks. Theoretically, our work is supplementary and contrastive to the mainstream second quantization method, and these spin-resolved results may be observed in future experiments.
Isotope and plasma size scaling in ion temperature gradient driven turbulence
Authors: Idomura Yasuhiro
Published: December 2019

This Letter presents the impacts of the hydrogen isotope mass and the normalized gyroradius ρ* on L-mode like hydrogen (H) and deuterium (D) plasmas dominated by ion temperature gradient driven (ITG) turbulence using global full-f gyrokinetic simulations. In ion heated numerical experiments with adiabatic electrons, the energy confinement time shows almost no isotope mass dependency and is determined by Bohm like ρ* scaling. Electron heated numerical experiments with kinetic electrons show clear isotope mass dependency caused by the isotope effect on the collisional energy transfer from electrons to ions, and the H and D plasmas show similar ion and electron temperature profiles at an H to D heating power ratio of ∼1.4. The normalized collisionless ion gyrokinetic equations for H and D plasmas become identical at the same ρ*, and collisions weakly affect ITG turbulence. Therefore, the isotope mass dependency is mainly contributed by the ρ* scaling and the heating sources.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: December 2019

In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials that supersede earlier data or suggest new research applications.
Optimal boundary control of nonlinear-viscous fluid flows
Authors: Baranovskii E. S.
Published: December 2019

The optimal control problem for a stationary model of a nonlinear-viscous incompressible fluid flowing through a bounded domain is considered under the wall slip condition. As a control parameter, the dynamic pressure at the in-flow and out-flow parts of the boundary is used. Using methods of the theory of pseudomonotone mappings, the existence of a weak solution (a velocity–dynamic pressure pair) minimizing a given cost functional is proved. The behaviour of solutions and optimal values of the cost functional are studied when the set of admissible controls varies. In particular, it is shown that the marginal function of this control system is lower semicontinuous.

Bibliography: 23 titles.
Perineuronal nets protect long-term memory by limiting activity-dependent inhibition from parvalbumin interneurons
Authors: Shi Wei , Wei Xiangbo , Wang Xiaofei , Du Shuwen , Liu Weixuan , Song Jian , Wang Yun
Published: December 2019

Significance

This study reveals the roles of PV interneurons surrounding perineuronal nets (PNNs) in both the hippocampus and the anterior cingulate cortex (ACC) in contextual fear memory. We show that increasing PNN expression in these 2 brain structures enhances the recall and reconsolidation of both recent and remote fear memory, corresponding to the enhancement of GABA-related theta oscillations. Conversely, removal of PNNs impairs consolidation and reconsolidation of both recent and remote fear memory via increased feedback inhibition and impairment of theta oscillations. Together, our results suggest that PNNs in the hippocampus and ACC affect behavioral plasticity during the consolidation and reconsolidation of contextual fear memory by regulating feedback inhibition of PV interneurons.
Precise timing is ubiquitous, consistent, and coordinated across a comprehensive, spike-resolved flight motor program
Authors: Putney Joy , Conn Rachel , Sponberg Simon
Published: December 2019

Significance

Brains can encode precise sensory stimuli, and specific motor systems also appear to be precise, but how important are millisecond changes in timing of neural spikes across the whole motor program for a behavior? We record nearly every spike that the hawk moth’s nervous system sends to its wing muscles. We show that all muscles convey the majority of their information in spike timing. The number of spikes does play a role, but not in a coordinated way across muscles. Instead, all coordination is done using the millisecond timing of spikes. The importance and prevalence of timing across the motor program pose questions for how nervous systems create precise, coordinated motor commands.
Descending projections from the
substantia nigra pars reticulata
differentially control seizures
Authors: Wicker Evan , Beck Veronica C. , Kulick-Soper Colin , Kulick-Soper Catherine V. , Hyder Safwan K. , Campos-Rodriguez Carolina , Khan Tahiyana , N’Gouemo Prosper , Forcelli Patrick A.
Published: December 2019

Significance

Identifying new targets for deep brain stimulation in epilepsy requires a deeper understanding of the brain networks engaged by seizure activity. For over 30 y, the
substantia nigra pars reticulata
has been recognized as a potential target, but the efferent pathways mediating the suppression of seizures have remained obscure. Here, we show that silencing the projection from the
substantia nigra
to the superior colliculus fully recapitulates the antiseizure effects evoked from cell bodies within the
substantia nigra
. By contrast, inhibition of the projection to the pedunculopontine nucleus exacerbates some seizures, reduces others, and is without effect on still others. The functional divergence of these pathways highlights a key role for projections to the superior colliculus in the control of seizures.
Satellite observations reveal extreme methane leakage from a natural gas well blowout
Authors: Pandey Sudhanshu , Gautam Ritesh , Houweling Sander , van der Gon Hugo Denier , Sadavarte Pankaj , Borsdorff Tobias , Hasekamp Otto , Landgraf Jochen , Tol Paul , van Kempen Tim , Hoogeveen Ruud , van Hees Richard , Hamburg Steven P. , Maasakkers Joannes D. , Aben Ilse
Published: December 2019

Methane emissions due to accidents in the oil and natural gas sector are very challenging to monitor, and hence are seldom considered in emission inventories and reporting. One of the main reasons is the lack of measurements during such events. Here we report the detection of large methane emissions from a gas well blowout in Ohio during February to March 2018 in the total column methane measurements from the spaceborne Tropospheric Monitoring Instrument (TROPOMI). From these data, we derive a methane emission rate of 120 ± 32 metric tons per hour. This hourly emission rate is twice that of the widely reported Aliso Canyon event in California in 2015. Assuming the detected emission represents the average rate for the 20-d blowout period, we find the total methane emission from the well blowout is comparable to one-quarter of the entire state of Ohio’s reported annual oil and natural gas methane emission, or, alternatively, a substantial fraction of the annual anthropogenic methane emissions from several European countries. Our work demonstrates the strength and effectiveness of routine satellite measurements in detecting and quantifying greenhouse gas emission from unpredictable events. In this specific case, the magnitude of a relatively unknown yet extremely large accidental leakage was revealed using measurements of TROPOMI in its routine global survey, providing quantitative assessment of associated methane emissions.
Stress-induced modulation of endocannabinoid signaling leads to delayed strengthening of synaptic connectivity in the amygdala
Authors: Yasmin Farhana , Colangeli Roberto , Morena Maria , Filipski Sarah , van der Stelt Mario , Pittman Quentin J. , Hillard Cecilia J. , Teskey G. Campbell , McEwen Bruce S. , Hill Matthew N. , Chattarji Sumantra
Published: December 2019

Significance

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric condition triggered by a brief traumatic event causing delayed and prolonged changes in emotional behaviors that are accompanied by amygdalar hyperactivity. Understanding of the underlying neuronal mechanisms during stress that eventually culminate in its delayed impact on the amygdala is limited. We found that oral administration, only during a brief stressor, of a pharmacological compound that elevates the levels of an endogenous ligand of cannabinoid receptors prevented both the immediate and delayed impact of acute stress on synaptic excitability in the amygdala of rats. This offers insights into potential therapeutic strategies for targeting endocannabinoid signaling to prevent the gradual development of affective symptoms and underlying amygdalar dysfunction triggered by traumatic stress.