bluuebunny/crossref_metadata_2025 huggingface dataset:
A multidirectional beam steering reflector actuated by hydraulic control
Authors: Liu Chao , Wang Di , Wang Qiong-Hua
Published: March 2019

This paper presents a multidirectional beam steering reflector (MBSR) actuated by hydraulic control. It consists of three substrates, an elastic membrane, a magnetic base and a mirror reflector (MR). The MR is fixed on the magnetic base and covered upon the top substrate. The bottom substrate is designed with three channels for pulling in/out the liquid. When liquid volume changes, the shape of the elastic membrane changes to form a liquid piston, accordingly. The liquid piston can make the MR rotate to different directions. When a light beam irradiates the MR, it can achieve the function of beam steering in latitude and longitude, simultaneously. Our experiments show that the proposed MBSR can deflect the light beam through a maximum angle of 0~12.7° in latitude and six-directions in longitude. The MBSR has potential applications in the fields of free-space optical communications, laser detections and solar cells.
Alternative reproductive adaptations predict asymmetric responses to climate change in lizards
Authors: Jara Manuel , García-Roa Roberto , Escobar Luis E. , Torres-Carvajal Omar , Pincheira-Donoso Daniel
Published: March 2019

Anthropogenic climate change ranks among the major global-scale threats to modern biodiversity. Extinction risks are known to increase via the interactions between rapid climatic alterations and environmentally-sensitive species traits that fail to adapt to those changes. Accumulating evidence reveals the influence of ecophysiological, ecological and phenological factors as drivers underlying demographic collapses that lead to population extinctions. However, the extent to which life-history traits influence population responses to climate change remains largely unexplored. The emerging ‘cul-de-sac hypothesis’ predicts that reptilian viviparity (‘live-bearing’ reproduction), a ‘key innovation’ facilitating historical invasions of cold climates, increases extinction risks under progressively warming climates compared to oviparous reproduction – as warming advances polewards/mountainwards, historically cold-climates shrink, leading viviparous species to face demographic collapses. We present the first large-scale test of this prediction based on multiple lizard radiations and on future projections of climate-based ecological niche models. Viviparous species were found to experience stronger elevational range shifts (and potentially increased extinctions) in coming decades, compared to oviparous lizards. Therefore, our analyses support the hypothesis’s fundamental prediction that elevational shifts are more severe in viviparous species, and highlight the role that life-history adaptations play in the responses of biodiversity to ongoing climate change.
Biochar phosphorus concentration dictates mycorrhizal colonisation, plant growth and soil phosphorus cycling
Authors: Solaiman Zakaria M. , Abbott Lynette K. , Murphy Daniel V.
Published: March 2019

We aimed to determine the relationship between biochar properties and colonisation of roots by arbuscular mycorrhizal (AM) fungi in agricultural soil. We used a range of biochars that differed in pH, water holding capacity, C, N and P concentrations to investigate interactions between biochar and AM fungi. A glasshouse experiment was conducted with subterranean clover and wheat, amended separately with 34 sources of biochar (applied at 1% w/w), to investigate potential responses in a phosphorus (P) deficient agricultural soil. Plant growth responses to biochar ranged from positive to negative and were dependent on biochar P concentration, available soil P and AM root colonisation. The higher the nutrient P concentration in biochar, the lower was AM colonisation. Growth responses of wheat and clover to the application of various biochars were mostly positive, and their growth was correlated, but biochar contributions to soil fertility varied with biochar properties. When nutrient concentrations are higher in biochars, especially for P and N, plants can gain access to nutrients via the plant roots and mycorrhizal hyphae. Thus biochar amendments can increase both plant nutrient uptake and crop production in nutrient deficient soil.
Soy isoflavones and their metabolites modulate cytokine-induced natural killer cell function
Authors: Mace Thomas A. , Ware Michael B. , King Samantha A. , Loftus Shannon , Farren Matthew R. , McMichael Elizabeth , Scoville Steven , Geraghty Connor , Young Gregory , Carson William E. , Clinton Steven K. , Lesinski Gregory B.
Published: March 2019

Soybeans are a rich source of isoflavones that have been linked with anti-inflammatory processes and various health benefits. However, specific mechanisms whereby soy bioactives impact immune cell subsets are unclear. Isoflavones, such as genistein and daidzein, are metabolized by microbes to bioactive metabolites as O-desmethylangolensin (O-DMA) and equol, whose presence has been linked to health benefits. We examined how soy isoflavones and metabolites impact natural killer (NK) cell signaling and function. We observe no impact of isoflavones on viability of healthy donor peripheral blood mononuclear cells (PBMCs) or NK cells, even at high (25 µM) concentrations. However, pre-treatment of PBMCs with physiologically-relevant concentrations of genistein (p = 0.0023) and equol (p = 0.006) decreases interleukin (IL)-12/IL-18-induced interferon-gamma (IFN-γ) production versus controls. Detailed cellular analyses indicate genistein and equol decrease IL-12/IL-18-induced IFN-γ production by human NK cell subsets, but do not consistently alter cytotoxicity. At the level of signal transduction, genistein decreases IL-12/IL-18-induced total phosphorylated tyrosine, and phosphorylation MAPK pathway components. Further, genistein limits IL-12/IL-18-mediated upregulation of IL-18Rα expression on NK cells (p = 0.0109). Finally,in vivostudies revealed that C57BL/6 mice fed a soy-enriched diet produce less plasma IFN-γ following administration of IL-12/IL-18 versus control-fed animals (p < 0.0001). This study provides insight into how dietary soy modulates NK cell functions.
SuPAR correlates with mortality and clinical severity in patients with necrotizing soft-tissue infections: results from a prospective, observational cohort study
Authors: Polzik Peter , Grøndal Olav , Tavenier Juliette , Madsen Martin B. , Andersen Ove , Hedetoft Morten , Hyldegaard Ole
Published: March 2019

Necrotizing soft tissue infections (NSTI) have a 90-day mortality rate of 18–22%. Tools are needed for estimating the prognosis and severity of NSTI upon admission. We evaluated soluble urokinase-type plasminogen activator receptor (suPAR) levels at admission as a prognostic marker of NSTI severity and mortality. In a prospective, observational cohort study, suPAR was measured in 200 NSTI patients. We compared admission suPAR levels in survivors and non-survivors, patients with septic shock and non-shock, amputation and non-amputation, correlations with Simplified Acute Physiology Score II (SAPS II) and the Sequential Organ Failure Assessment (SOFA) score. Admission suPAR levels were higher in septic shock vs. non-septic shock patients (9.2 vs. 5.8 ng/mL, p-value < 0.001) and non-survivors vs. survivors (11 vs. 6.1 ng/mL, p-value < 0.001) and correlated with SAPS II (r = 0.52, p < 0.001) and SOFA score (r = 0.64, p < 0.001). Elevated suPAR upon admission was associated with 90-day mortality (log-rank test p < 0.001), however not after adjustment for age, sex, and SOFA score. The AUC for suPAR and 90-day mortality was 0.77. We found that suPAR is a promising candidate for prognosis and severity in patients with NSTI.
Transcriptomic analysis of de novo folate biosynthetic genes in Lactobacillus plantarum strain 4_3 in fermented soybean
Authors: Liu Chen-Jian , Wu Bian , Zhang Si-Yao , Li Qiang-Kun , Zeng Xue-Qin , Yang En , Luo Yi-Yong , Li Xiao-Ran
Published: March 2019

Folate is an important intermediate in cellular metabolism.
Facile access to functionalized chiral secondary benzylic boronic esters via catalytic asymmetric hydroboration
Authors: Chakrabarty Suman , Palencia Hector , Morton Martha D. , Carr Ryan O. , Takacs James M.
Published: March 2019

Allylic and homoallylic phosphonates undergo asymmetric hydroboration yielding chiral boronic esters (yields up to 86%, enantiomer ratios up to 99 : 1).
A route to a cyclobutane-linked double-looped system via a helical macrocycle
Authors: Klajn Jan , Stawski Wojciech , Chmielewski Piotr J. , Cybińska Joanna , Pawlicki Miłosz
Published: March 2019

The macrocyclic confinements prefers a solid-state prearrangement of two CC linkers that after photocyclisation quantitatively form a cyclobutane linked double-looped structure with perpendicular orientation of macrocyclic arms.
Bond stretch isomerism in Be32−driven by the Renner–Teller effect
Authors: Homray Manoswita , Mondal Sukanta , Misra Anirban , Chattaraj P. K.
Published: March 2019

Illustration of bond stretch isomerization of triangularD3hBe32−moietiesviathe linearD∞hintermediate through the Renner–Teller effect. The reactant, intermediate and products are connected schematically by theC2vtransition states; moreover, a connection between the transition states and excited state linear intermediate is depicted.
Thermal stabilisation effects of Zr buffer layer on nanometric Rh overlayer catalyst formed on metal foil substrate
Authors: Yoshida Hiroshi , Misumi Satoshi , Matsumoto Akinori , Kuzuhara Yusuke , Sato Tetsuya , Ohyama Junya , Machida Masato
Published: March 2019

A nanometric Rh overlayer formed on a metal foil substrate enables much higher turnover frequencies in NO reduction than the Rh nanoparticles used in conventional three-way catalysis.
The mechanism of the gold-catalyzed intramolecular [3 + 2]-cycloaddition of 1,6-diynes: a DFT study
Authors: Lin Yongjia , Zhou Tao , Guo Wei , Teng Zhenfang , Xia Yuanzhi
Published: March 2019

The mechanism and selectivity of the gold-catalyzed intramolecular cycloaddition of 1,6-diynes were unveiled by DFT calculations.
Luminescent mechanochromism of gold N-heterocyclic carbene complexes with hypso- and bathochromic spectral shifts
Authors: Seki Tomohiro , Kashiyama Kentaro , Ito Hajime
Published: March 2019

Two gold N-heterocyclic carbene complexes show contrasting luminescent mechanochromism behavior with hypso- and bathochromic spectral shifts.
Distinguishing deposition, corrosion, and stripping of transient heterogeneous materials during molecular electrocatalysis
Authors: Sconyers David J. , Blakemore James D.
Published: March 2019

The electrochemical quartz crystal microbalance (EQCM) can readily detect formation of heterogeneous materials on electrode surfaces. Here, the behaviors of two cobaloxime-type catalysts for proton reduction have been investigated with EQCM, providing new insight into the involvement of transient heterogeneous materials in catalysis.
An indium–organic framework for the efficient storage of light hydrocarbons and selective removal of organic dyes
Authors: Huang Pan , Chen Cheng , Wu Mingyan , Jiang Feilong , Hong Maochun
Published: March 2019

An anionic indium–organic framework has been successfully prepared for the efficient absorption and separation of C2–C3 hydrocarbons from CH4as well as highly selective uptake of cationic organic dyes from anionic or neutral dyes.
Crystalline phase effect on the up-conversion processes and white emission of Yb3+/Er3+/Tm3+:Y2Si2O7 nanocrystals
Authors: Erdem Murat , Tabanli Sevcan , Eryurek Gonul , Samur Ramazan , Di Bartolo Baldassare
Published: March 2019

Observation of the crystalline phase depended spectral profiles. Shifting the cool white to the warm white with increasing power.
A facile one pot synthesis of thiazolo[3,2-a]benzimidazole and pyran fused polyheterocyclic scaffolds
Authors: Mariappan Arumugam , Rajaguru Kandasamy , Muthusubramanian Shanmugam , Bhuvanesh Nattamai
Published: March 2019

An efficient base catalysed synthesis of pyran fused benzimidazothiazoles by a multicomponent route starting from ω-2-benzimidothioacetophenone, an aromatic aldehyde and malononitrile is described.
Phosphine-catalyzed regiospecific (3 + 2) cyclization of 3-nitroindoles with allene esters
Authors: Jin Li-Wen , Jiang Fei , Chen Ke-Wei , Du Bai-Xiang , Mei Guang-Jian , Shi Feng
Published: March 2019

The title reaction has been established to construct indole-fused five-membered rings in good yields (up to 86%).
One-pot mild and efficient synthesis of [1,3]thiazino[3,2-a]indol-4-ones and their anti-proliferative activity
Authors: Rhodes Steven , Short Spencer , Sharma Sidhika , Kaur Ramneet , Jha Mukund
Published: March 2019

One-pot synthesis of [1,3]thiazino[3,2-a]indol-4-one frameworks is developed in aqueous medium and the anti-proliferative activity of the synthesized compounds is evaluated against two triple negative breast cancer cell lines.
A highly selective H/D exchange reaction of 1,4-dihydropyridines
Authors: Wang Kaiqian , Chen Xiaoping , Peng Xiao , Wang Ping , Liang Feng
Published: March 2019

A highly selective H/D exchange protocol of Hantzsch ester derivatives as well as related drugs was developed.
Synthesis, photophysical properties, and self-dimerization studies of 2-λ5-phosphaquinolin-2-ones
Authors: Bard Jeremy P. , Deng Chun-Lin , Richardson Hannah C. , Odulio Jacob M. , Barker Joshua E. , Zakharov Lev N. , Cheong Paul H.-Y. , Johnson Darren W. , Haley Michael M.
Published: March 2019

Rationally designed phosphaquinolinone derivatives containing electron-donating and/or -withdrawing groups are reported, with dimerization constants up to 525 M−1.
Weighted spectral reconstruction method for discrimination of bacterial species with low signal-to-noise ratio Raman measurements
Authors: Zhu Shanshan , Cui Xiaoyu , Xu Wenbin , Chen Shuo , Qian Wei
Published: March 2019

Raman spectra recovered from low SNR Raman measurements by weighted spectral reconstruction method show excellent preservation of information about bacterial identification.
Synthesis of d-glyco-alkynone derivatives via carbonylative Sonogashira reaction
Authors: Darbem Mariana P. , Esteves C. Henrique A. , de Oliveira Isadora M. , Reis Joel S. , Pimenta Daniel C. , Stefani Hélio A.
Published: March 2019

A carbonylative Sonogashira coupling approach to the synthesis of glyco-alkynones is described.
Homologous–heterogeneous structure control and intelligent adsorption effect of a polycationic gel for super-efficient purification of dyeing wastewater
Authors: Song Chunli , Li Hongyan , Yu Yikai
Published: March 2019

A homologous–heterogeneous polycationic gel (HPCG) system was constructed by a waste-free synthesis process, to be used as a super-efficient adsorbent material for purifying dyeing wastewater.
Exploring the thermal reversibility and tunability of a low molecular weight gelator using vibrational and electronic spectroscopy and rheology
Authors: DiGuiseppi David , Thursch Lavenia , Alvarez Nicolas J. , Schweitzer-Stenner Reinhard
Published: March 2019

The strength of metastable gels formed by self-assembly of GAG tripeptides in water can be tuned by annealing.
Designing bijels formed by solvent transfer induced phase separation with functional nanoparticles
Authors: Boakye-Ansah Stephen , Schwenger Matthew S. , Haase Martin F.
Published: March 2019

Functionalized silica nanoparticles with or without in situ surface modification are used to fabricate bijels via solvent transfer induced phase separation (STrIPS).
Rapid oxygen diffusive lithium–oxygen batteries using a restacking-inhibited, free-standing graphene cathode film
Authors: Jung In-Sun , Kwon Hyuk Jae , Kim Mokwon , Kim Doyoung , Kim Jung-Hwa , Lee Hyangsook , Yun Dongjin , Byun Sunjung , Yu Daeun , An Hyunju , Jang Jaeduck , Im Dongmin , Lee Hyoyoung
Published: March 2019

The rapid oxygen diffusion of corrugated 2D graphene sheets enhances the capacity and cycle life of lithium air batteries.
Electrochemical mechanisms of an advanced low-temperature fuel cell with a SrTiO3 electrolyte
Authors: Chen Gang , Liu Hailiang , He Yang , Zhang Linlin , Asghar Muhammad Imran , Geng Shujiang , Lund Peter D.
Published: March 2019

The electrochemical mechanisms and performance of a symmetrical low-temperature SOFC with a single oxide as the electrolyte are investigated here.
A novel method for fabrication of high-flux zeolite membranes on supports with arbitrary geometry
Authors: Yu Liang , Holmgren Allan , Hedlund Jonas
Published: March 2019

A new widely applicable masking method, relying on rendering the support hydrophobic and thereby protected from the synthesis mixture, was developed for the preparation of zeolite membranes on supports with arbitrary geometries.
An extraordinary cyclohexylmethyl side chain dominating polymeric donor packing patterns and energy levels for efficient non-fullerene polymer solar cells
Authors: Han Liangliang , Uranbileg Nergui , Jiang Shengshi , Xie Yu , Jiang Huanxiang , Lan Zhenggang , Yu Donghong , Bao Xichang , Yang Renqiang
Published: March 2019

A bulky cyclic side group admirably optimize the optical, electrochemical and crystalline characteristics of the donor polymers via its remarkable control on their polarities.
Designed synthesis of Ag-functionalized Ni-doped In2O3 nanorods with enhanced formaldehyde gas sensing properties
Authors: Zhang Xiaole , Song Dalei , Liu Qi , Chen Rongrong , Hou Jindi , Liu Jingyuan , Zhang Hongsen , Yu Jing , Liu Peili , Wang Jun
Published: March 2019

A new formaldehyde sensing material based on Ag-functionalized Ni-doped In2O3 nanorods was fabricated for easier detection of formaldehyde gas.
Bayesian Applications in Auditory Research
Authors: McMillan Garnett P. , Cannon John B.
Published: March 2019

Purpose

This article presents a basic exploration of Bayesian inference to inform researchers unfamiliar to this type of analysis of the many advantages this readily available approach provides.

Method

First, we demonstrate the development of Bayes' theorem, the cornerstone of Bayesian statistics, into an iterative process of updating priors. Working with a few assumptions, including normalcy and conjugacy of prior distribution, we express how one would calculate the posterior distribution using the prior distribution and the likelihood of the parameter. Next, we move to an example in auditory research by considering the effect of sound therapy for reducing the perceived loudness of tinnitus. In this case, as well as most real-world settings, we turn to Markov chain simulations because the assumptions allowing for easy calculations no longer hold. Using Markov chain Monte Carlo methods, we can illustrate several analysis solutions given by a straightforward Bayesian approach.

Conclusion

Bayesian methods are widely applicable and can help scientists overcome analysis problems, including how to include existing information, run interim analysis, achieve consensus through measurement, and, most importantly, interpret results correctly.

Supplemental Material

https://doi.org/10.23641/asha.7822592
The Evolution of Statistical Methods in Speech, Language, and Hearing Sciences
Authors: Oleson Jacob J. , Brown Grant D. , McCreery Ryan
Published: March 2019

Purpose

Scientists in the speech, language, and hearing sciences rely on statistical analyses to help reveal complex relationships and patterns in the data collected from their research studies. However, data from studies in the fields of communication sciences and disorders rarely conform to the underlying assumptions of many traditional statistical methods. Fortunately, the field of statistics provides many mature statistical techniques that can be used to meet today's challenges involving complex studies of behavioral data from humans. In this review article, we highlight several techniques and general approaches with promising application to analyses in the speech and hearing sciences.

Method

The goal of this review article is to provide an overview of potentially underutilized statistical methods with promising application in the speech, language, and hearing sciences.

Results

We offer suggestions to identify when alternative statistical approaches might be advantageous when analyzing proportion data and repeated measures data. We also introduce the Bayesian paradigm and statistical learning and offer suggestions for when a scientist might consider those methods.

Conclusion

Modern statistical techniques provide more flexibility and enable scientists to ask more direct and informative research questions.
Secure transmission in AF satellite system based on FH‐MWFRFT and null space beamforming
Authors: Xu Ruiyang , Da Xinyu , Liang Yuan , Ni Lei , Hu Hang
Published: March 2019

This study investigates the information security problem in amplify‐and‐forward (AF) satellite transmission with eavesdroppers at both the transmitter and the receiver. Two multi‐antenna earth stations aim to exchange messages through a multi‐antenna satellite in two hops. The satellite channels (both uplink and downlink) are assumed to be shadowed‐Rician fading. In the first hop, the multiple term weighted fractional Fourier transform (MWFRFT) is adopted to secure the messages from the eavesdropper at the transmitter. To overcome the simplicity of parameters in MWFRFT, the authors enhance the MWFRFT with frequency hopping and propose the frequency hopping multiple term weighted fractional Fourier transform (FH‐MWFRFT) to improve the secrecy. In the second hop, the satellite broadcasts the signal to the receiver after null space beamforming (NSBF). Since the energy at the satellite is confined, the NSBF is simplified by applying the singular value decompose to avoid the complicate optimisation calculations at the satellite. The one‐way and two‐way transmission scenarios with full channel state information (CSI) and statistic CSI are both considered in this study. Simulation results demonstrate the proposed method could achieve a better security at the transmitter while maintain a similar secrecy performance to the optimisation method at the legitimate receiver.
Integrating power assignment into energy‐efficient routing in E2E retransmission systems
Authors: Zhu Hai , Xu Mengmeng , Xu Hengzhou
Published: March 2019

Routing design is an effective mechanism to improve the energy‐efficiency in packet transmissions for wireless multihop networks. Meanwhile, the total energy consumption for packet transmissions over a path comprising of several unreliable links depends on the power assignment on each link. In this study, the authors address the energy‐efficient routing, which integrates with the optimal power assignment, in end‐to‐end (E2E) retransmission systems. The process of packet transmission across a path in E2E systems is modelled as a random walk. The expected energy consumed for the packet transmission is then calculated. As the expected energy consumption closely relies on the transmit power assigned on the path, it is necessary to integrate the power assignment into the energy‐efficient routing. The optimal power assignment on the candidate path is analytically derived for minimising the expected energy consumption. Specially, the energy‐efficient routing integrated with power sssignment (EERPA) algorithm is developed to find the optimal path among all candidate paths with all possible power assignments. Simulations demonstrate the efficiency of the authors' EERPA algorithm.
Use of hyperspectral imaging for cake moisture and hardness prediction
Authors: Polak Adam , Coutts Fraser K. , Murray Paul , Marshall Stephen
Published: March 2019

Industrial baking of sponge cakes requires various quality indicators to be measured during production such as moisture content and sponge hardness. Existing techniques for measuring these properties require randomly selected sponges to be removed from the production line before samples are manually cut out of each sponge in a destructive way for testing. These samples are subsequently processed manually using dedicated analysers to measure moisture and texture properties in a lengthy process, which can take a skilled operator around 20 min to complete per sponge. In this study, the authors present a new, single sensor hyperspectral imaging approach, which has the potential to measure both sponge moisture content and hardness simultaneously. In the last decade, hyperspectral imaging systems have reduced in cost and size and, as a result, they are becoming widely used in a number of industries and research areas. Recently, there has been an increased use of this technology in the food industry and in food science applications and research. The application of this technology in the cake production environment, empowered by sophisticated signal and image processing techniques and prediction algorithms as presented in this study has the potential to provide on‐line, real‐time, stand‐off cake quality monitoring.
FQI: feature‐based reduced‐reference image quality assessment method for screen content images
Authors: Rahul Kumar , Tiwari Anil Kumar
Published: March 2019

In this study, a reduced‐reference image‐quality‐assessment (IQA) method for screen content images, named as feature‐quality‐index (FQI) is proposed. The proposed method is based on the fact that the human visual system is more sensitive towards change in features than intensity or structure. Reduced features from the reference and distorted images are first extracted. In order to find the preserved features in the distorted image, a feature matching process with a reduced number of distance calculations is proposed, namely reduced‐distance method. To reflect the importance of the matched features and their distance, the inner product between the normalised scale and distance vector is obtained. Extensive comparisons are performed on two available benchmark databases namely SIQAD and QACS, with eight reduced‐reference, and nine full‐reference state‐of‐the‐art IQA techniques to demonstrate the consistency, accuracy, and robustness of the proposed FQI. The subjective evaluation of mean opinion score shows that FQI outperforms the current state‐of‐the‐art IQA techniques.
Exploiting transformation optics for arbitrary manipulation of antenna radiation pattern
Authors: Barati Hooman , Fakheri Mohammad Hosein , Abdolali Ali
Published: March 2019

Using transformation optics, a general method for tailoring the radiation pattern of a monopole antenna encompassed by a coating layer is proposed. Unlike previous studies, the propounded approach is not restricted to special patterns and can produce arbitrary radiation pattern with customisable beam parameters such as number, direction, and directivity in both azimuthal and elevation planes. A linear coordinate transformation is established to simplify the coating layer realisation via offering homogeneous materials. As proof‐of‐principle, two different antennas capable of generating multiple beams and a single‐directive beam, are elaborately acquired by a meta‐structure consisting of a split‐ring resonator‐wire array composite. It was observed that the experimental results corroborate numerical simulations. The proposed approach is believed to have potential applications in antenna technologies, satellite communication, and multiple‐input multiple‐output systems.
Efficient hybrid approach to the electromagnetic design of resonant cavities for side‐coupled linacs
Authors: Laneve Dario , Falconi Mario Christian , Bozzetti Michele , Rutigliani Giovanni , Prisco Raffaele Andrea , Dimiccoli Vincenzo , Prudenzano Francesco
Published: March 2019

A novel hybrid analytical/numerical approach, implemented via homemade code, is exploited to design the microwave cavities of a linear accelerator (linac) characterised by a very complex geometry. A finite element method‐based three‐dimensional investigation is integrated with a multi‐objective particle swarm optimisation technique in order to automatically design and optimise the geometry of the linac cavities. The cavity optimisation takes into account the typical figures of merit of a linac design. The hybrid approach is used to design a 27 MeV 3 GHz standing‐wave side‐coupled linac tank of 35 cavities including the end cells. The promising simulated results suggest that a global search approach is a useful and flexible tool for the electromagnetic design of accelerator cavities as well as other complex resonating multicavity structures.
Variability in X-ray line ratios in helium-like ions of massive stars: the wind-driven case
Authors: Ignace R. , Damrau Z. , Hole K. T.
Published: March 2019

Context. High spectral resolution and long exposure times are providing unprecedented levels of data quality of massive stars at X-ray wavelengths.

Aims. A key diagnostic of the X-ray emitting plasma are the fir lines for He-like triplets. In particular, owing to radiative pumping effects, the forbidden-to-intercombination line luminosity ratio, R = f∕i, can be used to determine the proximity of the hot plasma to the UV-bright photospheres of massive stars. Moreover, the era of large observing programs additionally allows for investigation of line variability.

Methods. This contribution is the second to explore how variability in the line ratio can provide new diagnostic information about distributed X-rays in a massive star wind. We focus on wind integration for total line luminosities, taking account of radiative pumping and stellar occultation. While the case of a variable stellar radiation field was explored in the first paper, the effects of wind variability are emphasized in this work.

Results. We formulate an expression for the ratio of line luminosities f∕i that closely resembles the classic expression for the on-the-spot result. While there are many ways to drive variability in the line ratio, we use variable mass loss as an illustrative example for wind integration, particularly since this produces no variability for the on-the-spot case. The f∕i ratio can be significantly modulated owing to evolving wind properties. The extent of the variation depends on how the timescale for the wind flow compares to the timescale over which the line emissivities change.

Conclusions. While a variety of factors can ellicit variable line ratios, a time-varying mass-loss rate serves to demonstrate the range of amplitude and phased-dependent behavior in f∕i line ratios. Importantly, we evaluate how variable mass loss might bias measures of f∕i. For observational exposures that are less than the timescale of variable mass loss, biased measures (relative to the time-averaged wind) can result; if exposures are long, the f∕i ratio is reflective of the time-averaged spherical wind.
Influence of collisions on ion dynamics in the inner comae of four comets
Authors: Mandt K. E. , Eriksson A. , Beth A. , Galand M. , Vigren E.
Published: March 2019

Context.Collisions between cometary neutrals in the inner coma of a comet and cometary ions that have been picked up into the solar wind flow and return to the coma lead to the formation of a broad inner boundary known as a collisionopause. This boundary is produced by a combination of charge transfer and chemical reactions, both of which are important at the location of the collisionopause boundary. Four spacecraft measured ion densities and velocities in the inner region of comets, exploring the part of the coma where an ion-neutral collisionopause boundary is expected to form.

Aims.The aims are to determine the dominant physics behind the formation of the ion-neutral collisionopause and to evaluate where this boundary has been observed by spacecraft.

Methods.We evaluated observations from three spacecraft at four different comets to determine if a collisionopause boundary was observed based on the reported ion velocities. We compared the measured location of the ion-neutral collisionopause with measurements of the collision cross sections to evaluate whether chemistry or charge exchange are more important at the location where the collisionopause is observed.

Results.Based on measurements of the cross sections for charge transfer and for chemical reactions, the boundary observed by Rosetta appears to be the location where chemistry becomes the more probable result of a collision between H2O and H2O+than charge exchange. Comparisons with ion observations made by Deep Space 1 at 19P/Borrelly andGiottoat 1P/Halley and 26P/Grigg-Skjellerup show that similar boundaries were observed at 19P/Borrelly and 1P/Halley. The ion composition measurements made byGiottoat Halley confirm that chemistry becomes more important inside of this boundary and that electron-ion dissociative recombination is a driver for the reported ion pileup boundary.
V643 Orionis: A detached, evolved, post-mass-exchange eclipsing binary
Authors: Andersen J. , Torres G. , Clausen J. V.
Published: March 2019

Context. One of the greatest uncertainties in modelling the mass-exchange phases during the evolution of a binary system is the quantity of mass and angular momentum that has been lost from the system. To constrain this problem, a favourable, evolved, and detached real binary system is valuable as an example of the end result of this process.

Aims. We study the 52-day post-mass-exchange eclipsing binary V643 Ori from complete uvby light curves and high-resolution spectra. V643 Ori is double-lined and shows total primary eclipses. The orbit is accurately circular and the rotation of the two stars is synchronised with the orbit, but the photometry from a single year (1993) shows signs of weak spot activity (0.02 mag) around the primary eclipse.

Results. We determined accurate masses of 3.3 and 1.9 M⊙ from the spectroscopic orbit and solved the four light curves to determine radii of 16 and 21 R⊙, using the Wilson-Devinney photometric code. The rotational velocities from the cross-correlation profiles agree well with those computed from the known radii and orbital parameters. All observable parameters are thus very precisely determined, but the masses and radii of V643 Ori are incompatible with undisturbed post-main-sequence evolution.

Conclusions. We have attempted to simulate the past evolutionary history of V643 Ori under both conservative and non-conservative Case B mass transfer scenarios. In the non-conservative case we varied the amounts of mass and angular momentum loss needed to arrive at the present masses in a circular 52-day orbit, keeping the two stars detached and synchronised as now observed, but without following the evolution of other stellar properties in any detail. Multiple possible solutions were found. Further attempts were made using both the BSE formalism and the binary MESA code in order to track stellar evolution more closely, and make use of the measured radii and temperatures as important additional constraints. Those efforts yielded no satisfactory solutions, possibly due to limitations in handling mass transfer in evolved stars such as these. We remain hopeful that future theoreticians can more fully model the system under realistic conditions.
Outgassing-induced acceleration of comet 67P/Churyumov-Gerasimenko
Authors: Kramer T. , Läuter M.
Published: March 2019

Context. Cometary activity affects the orbital motion and rotation state through sublimation-induced forces. The availability of precise rotation-axis orientation and position data from the Rosetta mission allows us to accurately determine the outgassing of comet Churyumov-Gerasimenko/67P (67P).

Aims. We derived the observed non-gravitational acceleration of 67P directly from the trajectory of the Rosetta spacecraft. From the non-gravitational acceleration, we recovered the diurnal outgassing variations and study a possible delay of the sublimation response with respect to the peak of the solar illumination. This allowed us to compare the non-gravitational acceleration of 67P with expectations based on empirical models and common assumptions about the sublimation process.

Methods. We used an iterative orbit refinement and Fourier decomposition of the diurnal activity to derive the outgassing-induced non-gravitational acceleration. The uncertainties of the data reduction were established by a sensitivity analysis of an ensemble of best-fit orbits for comet 67P.

Results. We find that the Marsden non-gravitational acceleration parameters reproduce part of the non-gravitational acceleration, but need to be augmented by an analysis of the nucleus geometry and surface illumination to draw conclusions about the sublimation process on the surface. The non-gravitational acceleration closely follows the subsolar latitude (seasonal illumination), with a small lag angle with respect to local noon around perihelion. The observed minor changes of the rotation axis do not favor forced precession models for the non-gravitational acceleration.

Conclusions. In contrast to the sublimation-induced torques, the non-gravitational acceleration does not place strong constraints on localized active areas on the nucleus. We find a close agreement of the orbit-deduced non-gravitational acceleration and the water production that is independently derived from Rosetta in situ measurements.
Improved regularity assumptions for partial outer convexification of mixed-integer PDE-constrained optimization problems
Authors: Manns Paul , Kirches Christian
Published: March 2019

Partial outer convexification is a relaxation technique for MIOCPs being constrained by time-dependent differential equations. Sum-Up-Rounding algorithms allow to approximate feasible points of the relaxed, convexified continuous problem with binary ones that are feasible up to an arbitrarily smallδ> 0. We show that this approximation property holds for ODEs and semilinear PDEs under mild regularity assumptions on the nonlinearity and the solution trajectory of the PDE. In particular, requirements of differentiability and uniformly bounded derivatives on the involved functions from previous work are not necessary to show convergence of the method.
Anomalous absorption in ECRH experiments due to the parametric low-threshold excitation of localized UH waves
Authors: Popov Alexei Yu. , Gusakov Evgeniy Z.
Published: March 2019

We describe the theoretical model which interprets the anomalous phenomena, i.e. the generation of backscattering signal observed in the ECRH experiments at TEXTOR, TCV, TJ-II, ASDEX-UG, LHD and FTU, as a consequence of the excitation of the parametric decay instability (PDI) leading to anomalous damping of the pump wave. The PDI power-threshold is shown to be extremely low due to the localization of both or one daughter upper hybrid (UH) waves in presence of a nonmonotonic (hollow) density profile, which is often observed in the ECRH experiments due to the magnetic island or the density pump-out effect. In the case of the extraordinary wave pump the model predicts substantial (up to 25%) anomalous absorption in the electron channel and explains the anomalous ion acceleration by the generation of secondary low frequency waves which directly transfer the pump power to the ion component. The possibility of anomalous absorption of the O-mode pump in the ECRH experiment due to the parametric excitation of trapped UH wave is also discussed and the anomalous absorption rate at the 10% level is predicted.
ECCD operations in the second experimental campaign at W7-X
Authors: Zanini M. , Laqua H.P. , Stange T. , Brandt C. , Hirsch M. , Höfel U. , Marushchenko N. , Neuner U. , Rahbarnia K. , Schilling J. , Thomsen H. , Wolf R.C. ,   W7-X Team
Published: March 2019

In the Wendelstein 7-X stellarator, up to 7MW of power are delivered to the plasma by an electron cyclotron resonance heating system consisting of ten 140 GHz gyrotrons [1].

Due to the flexible front steering mirror of each beam line, the power deposition can be varied over the whole plasma radius and is optionally combinable with additional current drive. This flexibility, together with small toroidal currents in the stellarator, makes W7-X a perfect testbed for electron cyclotron current drive (ECCD) experiments, which have been successfully accomplished during the first two experimental campaigns OP1.1 and OP1.2a.

Long discharges (lasting up to 30s) have been performed in OP1.2a, thus allowing the study of the current drive time evolution and the possibility to compensate the bootstrap current.

ECCD efficiency has been studied using different power deposition profiles combined with a variation of the injection angles in relation to the magnetic field.

During ECCD experiments, saw-tooth-like oscillations have been observed. Depending on the driven current density, ECCD can significantly modify the rotational transform (iota) profile, which can locally reach low order rational, thus triggering plasma instabilities.

Different current density profiles have been tested, in order to try to understand the main trigger parameter for the instabilities. In particular, effects caused by current density gradient have been investigated producing both co- and counter-current drive at different radial positions: the total current drive is negligible, but a strong current gradient arises by driving currents in opposite directions.

In this work an overview of ECCD operations in OP1.2a is given and first results, comparing different diagnostics, are presented. An initial 1-D model, coupled with the ray tracer TRAVIS, is developed, in order to have an estimation of current diffusion times and the radial position where a low order rational crosses the disturbed iota profile.
Progress in ITER ECE Diagnostic Design and Integration
Authors: Udintsev V.S. , Danani S. , Taylor G. , Giacomin T. , Guirao J. , Pak S. , Hughes S. , Worth L. , Vayakis G. , Walsh M.J. , Schneider M. , Pandya H.K.B. , Kumar R. , Kumar V. , Jha S. , Thomas S. , Padasalagi S. B. , Kumar S. , Phillips P. E. , Rowan W. L. , Austin M.E. , Khodak A. , Feder R. , Neilson H. , Basile A. , Hubbard A. E. , Saxena A. , Nazare C. , Maquet P. , Gimbert N.
Published: March 2019

The ITER Electron Cyclotron Emission (ECE) diagnostic is progressing towards its Preliminary Design Review (PDR). In parallel, the diagnostic integration in the Equatorial Port is ongoing. Port Integration has to address the structural integrity to withstand various loads, maintenance and the safety aspects of ECE diagnostic. The ITER ECE system includes radial and oblique lines-of-sight. Recently, a successful peer-review of the in-port plug Hot Calibration Source has taken place and its performance and integration feasibility has been demonstrated. Four 45-meter long low-loss transmission lines are designed to transmit mm-wave power in the frequency range of 70- 1000 GHz in both X- and O-mode polarization from the port plug to the ECE instrumentation room in the diagnostic building. Prototype transmission lines are being tested [1]. A prototype polarizing Martin-Puplett type Fourier Transform Spectrometer (FTS) operating in the frequency range 70-1000 GHz, has a fast scanning mechanism and a cryo-cooled dual-channel THz detector system. Its performance has been tested as per ITER requirements. Assessment of the instrumentation and control requirements, functional and non-functional requirements, operation procedures, plant automation are ongoing for the PDR. The current status of the diagnostic, together with integration activities, is presented.
Overview of the ECE measurements on EAST
Authors: Liu Yong , Zhao Hailin , Zhou Tianfu , Liu Xiang , Zhu Zeying , Han Xiang , Schmuck Stefan , Fessey John , Trimble Paul , Domier C.W. , Luhmann N.C. , Ti Ang , Li Erzhong , Ling Bili , Hu Liqun , Feng Xi , Liu Ahdi , Rowan W.L. , Huang He , Phillips P.E. , Figini Lorenzo
Published: March 2019

Radiometer systems and a Michelson interferometer, have been operated routinely to detect the elec-tron cyclotron emission (ECE) from EAST plasmas for diagnosing the local electron temperature. A common quasi-optical antenna placed inside the vacuum vessel is employed to collect and focus the plasma emission, and the line of sight is along a radial chord. All of the systems are located in a diagnostic room where the plasma emission is transmitted by overmoded corrugated waveguide. In-situ absolute intensity calibration has been carried out for both the radiometer systems and the Michelson interferometer independently, to ensure that the ECE diagnostic provides an independent electron temperature measurement. In order to diagnose the small-amplitude electron temperature fluctuation, a correlation ECE (CECE) diagnostic has been designed and commissioned recently. The CECE diagnostic employs an independent antenna system which has improved poloidal resolution. A synthetic diagnostic is realized by using the simulation code SPECE to interpret the ECE data in plasmas with non-Maxwellian distribution, and preliminary results imply that the ECE data could be still useful as a localized measurement in plasmas with non-thermal electrons, such as the LHW-heated plasmas on EAST.
Intense intermittent radiation at the plasma frequency on EAST
Authors: Liu Yong , Zhou Tianfu , Hu Yemin , Zhao Hailin , Zhu Zeying , Liu Xiang , Ling Bili , Zhou Ruijie , Zhang Tao
Published: March 2019

Intense intermittent radiation has been observed regularly in EAST by using a Michelson interfer-ometer and a Q-band radiometer system. The radiation bursts are related to a fast process with characterization time of a few microseconds. An electron density window exists for the occurrence of the bursts, and the upper electron density threshold is dependent of the toroidal magnetic field. The frequency of the emission f is at the plasma frequency, and the frequency bandwidth Δ f is very narrow (∼1.5 MHz FWHM, Δ f / f ∼ 3 × 10−5). Fine structure of the spectrum with multi-peaks have been observed, and the frequency interval is around 3 MHz. Numerical simulation results of cavity modes indicate that the frequencies of these modes are close to the central plasma frequency, and the departure from the central plasma frequency becomes larger for higher order modes.
Adaptation of a Dual-Frequency 104/140 GHz Gyrotron for Operation at 175 GHz
Authors: Cauffman Stephen , Blank Monica , Borchard Philipp , Felch Kevin
Published: March 2019

A dual-frequency gyrotron capable of operation in the TE28,7 cavity interaction mode at 140 GHz, or in the TE22,5 mode at 104 GHz, has been developed for use in electron cyclotron heating in the W7-X stellarator at IPP Greifswald. The gyrotron incorporates an internal converter design that has been numerically optimized to convert either of the two operating modes into a high-quality Gaussian output beam. During short-pulse factory testing, the gyrotron produced 900 kW at 140 GHz, and 520 kW at 104 GHz. After delivery to IPP, the gyrotron was conditioned to long-pulse operation at 140 GHz, demonstrating 30-minute pulses at several power levels up to 811 kW, and producing ten consecutive ten-minute pulses at 811 kW as well. After long-pulse capabilities were demonstrated at 140 GHz, IPP requested an analysis of the feasibility of operating the gyrotron (without internal modification) in an additional mode with a frequency near 175 GHz. Several potential interaction modes were evaluated to determine the required operating parameters for excitation of these modes, and to assess the expected interaction efficiency, output power, internal diffraction losses, and output beam quality. The most promising modes appear to be the TE33,9 (173 GHz) and the TE34,9 (176 GHz), which should generate 400-500 kW of RF in a suitable magnet capable of producing the necessary 7.1 T field required for operation at these higher frequencies. Because the existing gyrotron’s internal converter was not optimized for these modes, however, internal losses are expected to be higher than usual (up to 7%), and the output beam pattern will require external phase-correction in order to produce a Gaussian beam. A feasibility analysis for such external phase correction has been performed, demonstrating that a high-quality beam can be recovered using numerically synthesized external phase-correcting mirror surfaces.