bluuebunny/crossref_metadata_2025 huggingface dataset:
Detectability of shape deformation in short-period exoplanets
Authors: Akinsanmi B. , Barros S. C. C. , Santos N. C. , Correia A. C. M. , Maxted P. F. L. , Boué G. , Laskar J.
Published: December 2018

Context.Short-period planets are influenced by the extreme tidal forces of their parent stars. These forces deform the planets causing them to attain nonspherical shapes. The nonspherical shapes, modeled here as triaxial ellipsoids, can have an impact on the observed transit light-curves and the parameters derived for these planets.

Aims.We investigate the detectability of tidal deformation in short-period planets from their transit light curves and the instrumental precision needed. We also aim to show how detecting planet deformation allows us to obtain an observational estimate of the second fluid Love number from the light curve, which provides valuable information about the internal structure of the planet.

Methods.We adopted a model to calculate the shape of a planet due to the external potentials acting on it and used this model to modify theellctransit tool. We used the modifiedellcto generate the transit light curve for a deformed planet. Our model is parameterized by the Love number; therefore, for a given light curve we can derive the value of the Love number that best matches the observations.

Results.We simulated the known cases of WASP-103b and WASP-121b which are expected to be highly deformed. Our analyses show that instrumental precision ≤50 ppm min−1is required to reliably estimate the Love number and detect tidal deformation. This precision can be achieved for WASP-103b in ∼40 transits using theHubbleSpace Telescope and in ∼300 transits using the forthcoming CHEOPS instrument. However, fewer transits will be required for short-period planets that may be found around bright stars in the TESS and PLATO survey missions. The unprecedented precisions expected from PLATO and JWST will permit the detection of shape deformation with a single transit observation. However, the effects of instrumental and astrophysical noise must be considered as they can increase the number of transits required to reach the 50 ppm min−1detection limit. We also show that improper modeling of limb darkening can act to bury signals related to the shape of the planet, thereby leading us to infer sphericity for a deformed planet. Accurate determination of the limb darkening coefficients is therefore required to confirm planet deformation.
Modeling and removal of optical ghosts in the PROBA-3/ASPIICS externally occulted solar coronagraph
Authors: Shestov S. V. , Zhukov A. N. , Seaton D. B.
Published: December 2018

Context. ASPIICS is a novel externally occulted solar coronagraph, which will be launched onboard the PROBA-3 mission of the European Space Agency. The external occulter will be placed on the first satellite ∼150 m ahead of the second satellite that will carry an optical instrument. For 6 h per orbit, the satellites will fly in a precise formation, constituting a giant externally occulted coronagraph. The large distance between the external occulter and the primary objective will allow observations of the white-light solar corona starting from extremely low heights ∼1.1 R⊙.

Aims. We aim to analyze the possible influence of optical ghost images formed inside the telescope and to develop an algorithm for their removal.

Methods. We implement the optical layout of ASPIICS in Zemax and study the ghost behavior in sequential and nonsequential regimes. We identify sources of the ghost contributions and analyze their geometrical behavior. Finally we develop a mathematical model and software to calculate ghost images for any given input image.

Results. We show that ghost light can be important in the outer part of the field of view, where the coronal signal is weak, since the energy of bright inner corona is redistributed to the outer corona. However, the model allows for the ghost contribution to be removed. Due to the large distance between the external occulter and the primary objective, the primary objective does not produce a significant ghost. The use of the Lyot spot in ASPIICS is not necessary.
Loss analysis in luminescent sheet concentrators: from ideal to real system
Authors: Proise Florian , Joudrier Anne-Laure , Pelouard Jean-Luc , Guillemoles Jean-François
Published: December 2018

Thermodynamic limits of luminescent sheet concentrators (LSC) are three orders of magnitude higher than record ones made up to now. This paper aims at understanding why there is such a gap and what is the link between ideal and real LSC. Computational modeling enables to evaluate separately the different loss mechanisms, to determine their respective weight, and to correlate them to accessible physical parameters, such as geometrical ratio, photoluminescence quantum yield, etc. From an ideal system, the different parameters have been degraded to obtain a real system and the performances of each system have been simulated. The high interdependency of different loss mechanisms has also been studied in several cases. In a second part, more realistic cases are addressed to show how performances is impacted by non-idealities and where does the principal limitations come from. Practically achievable efficiencies are suggested, based on state-of-the-art technologies and material properties. Finally, promising directions for the search of better systems are proposed.
Research on Variable Cycle Engine Control Based on Model Reference Adaptive Sliding Mode Control Method
Authors: Xiao Hongliang , Li Huacong , Li Jia , Fu Jiangfeng , Peng Kai
Published: December 2018

As to solve the problem of multivariable output tracking control of variable cycle engine under system uncertainties and external disturbances, an augmented model reference adaptive sliding mode control method based on LQR method was developed. Firstly, the model is augmented and the reference state is provided to the controller by designing the reference model using the optimal LQR method. Then, based on the state tracking sliding mode control method, the adaptive law is derived based on the strict stability condition of Lyapunov function to estimate the upper bound of the system perturbation matrix and the upper bound of the external disturbances. Finally, the controller achieves the asymptotic zero tracking error of the system under the conditions of uncertainty and external disturbance. The simulation results showed that the LQR-based augmented model reference adaptive sliding mode control method can solve the problem that the traditional sliding mode control method needs to specify the reference state in advance and improve the control performance of the variable cycle engine control with system uncertainties and external disturbance. The tracking of the control command is effectively achieved and the steady-state and dynamic performance are improved. The steady-state control errors under different conditions are less than 0.1%, the system overshoot is less than 0.5%, and the adjustment time is less than 1s, which conformed to the requirements of the aero engine control system technology.
MR Damper-Based Vibration Suppression Method for Control Moment Gyroscope
Authors: Wang Wendong , Ming Xing , Chu Yang , Liu Minghui , Shi Yikai
Published: December 2018

To restrain the interference of micro-vibration caused by Control Moment Gyroscope, a new control method based on Magnetorheological damper was proposed in this paper. A mechanical model based on the structure of the presented design was built, and the semi-active control algorithm of damping force was proposed for the designed Magnetorheological damper. The magnetic flux density and other magnetic field parameters were considered and analyzed in Maxwell, and also the related hardware circuit which implements the control algorithm was prepared to test the presented design and algorithm. The results of simulation and experiments show that the presented Magnetorheological damper model and semi-active control algorithm can complete the requirements, and the vibration suppression method is efficient for Control Moment Gyroscope.
Fast Access for Star Catalog Based on Locality-Sensitive Hashing
Authors: Zhu Hailong , Liang Bin , Zhang Tao
Published: December 2018

In order to improve the access speed and robustness of star catalog database during star identification, an algorithm based on locality-sensitive hashing is proposed. First, according to principle of star identification, the angle distances are quantified on the basis of angle distance error limit, and the order star set pattern is transformed into an array of integers, which has locally sensitive hash characteristics. Then key of hash obtain by hashing the array of integers with Stlport, and the value of hashing is a set of central star number in the ordered star point set pattern. Numerical simulation results indicate that the time complexity of proposed algorithm is O(1), which is much better than direct search, binary search and k-vector search technology. In addition, the proposed algorithm is robustness due to the affect is not significant as the performance influenced by angle distance error limit. Considering practical application, the error limit of angle distance could be chose as 1 pixel, the number of quantified angle distances could be chosen as 3. Under this condition, the collision rate in hashing table is 0.74%, the average searching time is 1.007 4 and the average consuming time is 22 μs during star identification.
Diet of invasive pikeperchSander lucioperca: developing non-destructive tissue sampling for stable isotope analysis with comparisons to stomach contents analysis
Authors: Nolan Emma T. , Britton J. Robert
Published: December 2018

Impact assessments of invasive piscivorous fishes usually rely on dietary analyses to quantify their predation pressure on prey communities. Stomach contents analysis (SCA), typically a destructive sampling method, is frequently used for this. However, many invasive piscivores are exploited by catch-and-release sport angling, with destructive sampling often not feasible. Stable isotope analysis (SIA) provides an alternative dietary analysis tool to SCA, with use of fin tissue, scales and/or epidermal mucus potentially enabling its non-destructive application. Here, the diet of a population of pikeperchSander lucioperca, an invasive sport fish to Great Britain, was investigated by applying SIA to a range of tissues. Testing SI data of dorsal muscle (destructive sampling) versus fin, scale and mucus (non-destructive sampling) revealed highly significant relationships, indicating that the tissues collected non-destructively can be reliably applied to pikeperch diet assessments. Application of these SI data to Bayesian mixing models predicted that asS. luciopercalength increased, their diet shifted from macro-invertebrates to fish. Although similar ontogenetic patterns were evident in SCA, this was inhibited by 54% of fish having empty stomachs. Nevertheless, SCA revealed that asS. luciopercalength increased, their prey size significantly increased. However, the prey:predator length ratios ranged between 0.08 and 0.38, indicating most prey were relatively small. These results suggest that when non-destructive sampling is required for dietary analyses of sport fishes, SIA can be applied using fin, scales and/ or mucus. However, where destructive sampling has been completed, SCA provides complementary dietary insights, especially in relation to prey size.
Injection of ropivacaine combined with pregabalin in a patient with post-traumatic trigeminal neuropathic pain
Authors: Tisné-Versailles Sophie , Fénélon Mathilde , Marteau Jean-Marie , Catros Sylvain , Fricain Jean-Christophe
Published: December 2018

Introduction: Post-traumatic painful trigeminal neuropathy is a chronic facial pain secondary to trigeminal nerve injury. The treatment of this pain is a therapeutic issue due to the alteration of quality of life that it generates. Observation: A 58-year-old man whose main history of facial trauma has been consulted in the Odontology Department for bilateral trigeminal neuropathic pain that has been evolving for several months. The interrogation revealed continuous pain like electric shocks in the canine areas and daily painful exacerbations. Hyperesthesia and allodynia were found on clinical examination. The patient had received several treatments, oral and local, without significant improvement. As a last resort, injections of ropivacaine every 2 weeks associated with pregabalin (200 mg/day) were performed. At 6 months, there was a clear decrease in the burning sensation and a complete disappearance of painful exacerbations. Discussion: Two studies have recently shown the benefit of the combination of an antiepileptic and a local analgesic in the treatment of classical trigeminal neuralgia, justifying their use in a context of post-traumatic neuropathic pain. Conclusion: Further studies with higher levels of evidence are needed to confirm these preliminary results.
Sucht und Adipositas: Können Nahrungsmittel abhängig machen?
Authors: Bumb J. , Weber Tillmann , Kiefer Falk
Published: December 2018

Die weltweite Prävalenz von Übergewicht und Adipositas nimmt in den letzten Jahren sowohl bei Kindern und Jugendlichen als auch bei Erwachsenen stetig zu. Hiermit verbunden sind zahlreiche Folgeerkrankungen, die zu einer reduzierten Lebensqualität, einer reduzierten Lebenserwartung und hohen direkten und indirekten Gesundheitskosten führen. Ein zentraler Aspekt der aktuellen Forschung beschäftigt sich mit der Frage, ob abhängige Verhaltensweisen im Zusammenhang mit dem derzeit bestehenden Überangebot an billiger, „schmackhafter“ (hoher Anteil an Zucker, Fett, Salz oder an Lebensmittelzusatzstoffen wie Geschmacksverstärkern) Nahrung zur steigenden Prävalenz der Adipositas beitragen könnten. Eine Verbesserung des Verständnisses der Wirkung bestimmter Nahrungsbestandteile auf Prozesse von Präferenz und Verhaltenssteuerung birgt die Hoffnung, neue und effizientere Therapieformen entwickeln zu können. Um diesen aktuellen Sachverhalt näher zu beleuchten, führten die Autoren eine selektive PubMed Recherche zu den Themen „obesity AND addiction“ durch. Aus der Literaturrecherche ergeben sich Hinweise für Gemeinsamkeiten in Prozessen und Regelkreisläufen, die sowohl bei der Entstehung und der Aufrechterhaltung der Adipositas als auch von Abhängigkeitserkrankungen eine Rolle spielen. Konkret sind hier phänomenologische und klinische, neuroendokrinologische und bildgebende Aspekte sowie Gemeinsamkeiten, bestimmte Transmittersysteme betreffend, zu nennen. Bei der Ergänzung der etablierten und der Entwicklung zukünftiger, innovativer und multi-modaler Therapieansätze sollten Suchtmechanismen und motivationale Aspekte der Nahrungsaufnahme bei der Behandlung der Adipositas daher Beachtung finden.
Concise Asymmetric Synthesis of Kweichowenol A
Authors: Konrad David , Kicin Bilal , Trauner Dirk
Published: December 2018

An asymmetric 11-step synthesis of the polyoxygenated cyclohexene natural product kweichowenol A from the traditional Chinese medicinal herb Uvaria kweichowesis is reported. The oxygenation pattern was installed on a linear precursor by exploiting the acyclic stereocontrol of the Kiyooka aldol reaction, as well as Cram chelate-controlled Grignard reactions. Ring-closing metathesis and a selective benzoylation then gave the natural product.
Visible-Light-Induced Aerobic Oxidation of Benzylic C(sp3)–H of Alkylarenes Promoted by DDQ, tert-Butyl Nitrite, and Acetic Acid
Authors: Shen Zhenlu , Pan Decheng , Wang Yiqing , Li Meichao , Hu Xinquan , Sun Nan , Jin Liqun , Hu Baoxiang
Published: December 2018

A visible-light photocatalytic aerobic oxidation of benzylic C(sp3)–H bonds proceeded in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, tert-butyl nitrite, and acetic acid. Advantages of this aerobic oxidation method include its relatively mild conditions, the use of visible-light irradiation instead of conventional thermal methods, the use of a low catalyst loading, and the ability to oxidize a range of alkyl­arenes, including xanthenes, thioxanthenes, and 9,10-dihydroacridines, to the corresponding ketones in excellent yields.
The Gut Microbiota as an Influencing Factor of Arterial Thrombosis
Authors: Reinhardt Christoph
Published: December 2018

The mutualistic gut microbiota does not only impact the development and function of various immune cell types, but it also influences the function of the hepatic vascular endothelium and prothrombotic platelet function. With germ-free mouse models, we have demonstrated that gut-derived microbial-associated molecular patterns could stimulate hepatic von Willebrand factor (VWF) synthesis and plasmatic VWF levels through Toll-like receptor-2 (TLR2), thus defining the extent of platelet deposition to the subendothelial matrix of the ligation-injured common carotid artery. In addition to the microbiota-derived choline metabolite trimethylamine N-oxide and the microbiota's regulatory role on the colonic serotonin biosynthesis pathway, affecting prothrombotic platelet function, TLR2-regulated hepatic endothelial VWF synthesis and elevated VWF plasma levels constitute a pivotal mechanism of how the gut microbiota is linked to arterial thrombosis. Conceptually, in addition to the identified functions of the gut microbiota in modulating host nutrition and metabolism, our work places the innate immune functions of the liver sinusoidal endothelium as an actuating variable in arterial thrombus growth.
Responding to volcanic eruptions in Iceland: from the small to the catastrophic
Authors: Bird Deanne K. , Gísladóttir Guðrún
Published: December 2018

There is no doubt that as the world’s population continues to grow and expand in hazardous environments, so too does our vulnerability to disaster. Researching disaster risk is therefore an ongoing challenge requiring a continual process of generating understanding of the changing environmental and societal characteristics that influence disaster vulnerability. Iceland, as the land of fire and ice, is of no exception. With a changing population, exponential growth in tourism and a volcanic eruption on average every 3–4 years, disaster risk research is of critical importance. Based on questionnaire survey results, interviews with key stakeholders and data derived from Statistics Iceland, this paper considers how residents might respond to a future eruption by examining their experience of the 2010 Eyjafjallajökull eruptions against the changing demographic, economic and political landscape. While authorities were pleased with public response to evacuation orders in 2010, some residents did not evacuate. The reasons for not evacuating were due to caring for others or thinking the warnings were not applicable. Yet, most residents showed respect for authority and acknowledged the necessity of the evacuations. The relatively small, homogenous population of Iceland coupled with its peoples’ desire to cooperate contributed to this success. Within these communities, people are bound together by common beliefs, values and activities. However, the changing social landscape will test this phenomenon. In particular, the region’s economic base is evolving from traditional farming practices to one that is increasingly reliant on tourism. Demographic changes most notably include greater international migration to the South, as well as from the capital region. As the communities diversify, so too will people’s beliefs, values and activities. This paper explores the challenges this diversity brings with respect to generating a proactive public response to future evacuation orders. Furthermore, it highlights the importance of capturing narratives of actions and activities to enhance our understanding of the process of decision-making and the situational factors that add to its complexity.
Aperiodic multilayer graphene based tunable and switchable thermal emitter at mid-infrared frequencies
Authors: Sharifi S. , Banadaki Y. M. , Nezhad V. F. , Veronis G. , Dowling J. P.
Published: December 2018

Graphene attracts enormous interest for photonic applications as it provides a degree of freedom to manipulate electromagnetic waves. In this paper, we present new graphene-based aperiodic multilayer structures as selective, tunable, and switchable thermal emitters at infrared frequencies. For these optimized aperiodic thermal emitters, we investigate the effect of the chemical potential and number of graphene layers on the range of selectivity, tunability, and switchability of thermal emittance. We find that the proposed thermal emitters show about an order of magnitude narrower thermal band, e.g., improved selectivity. The tunability of thermal power emitted from the structure with 32 graphene layers is ∼3.5 times larger than that of the structure with eight graphene layers, changing from λ=3.34μmto2.85μm by increasing the chemical potential from 0.0 eV to 1.0 eV. We demonstrate that the arrangement with 32 graphene layers can decrease by ∼83% of the power emitted for λ=3.34μm, providing ∼4.5 times stronger switchability than for the structure with eight graphene layers. The electrically dynamic control of the proposed graphene-based aperiodic multilayer structures can pave the way for a new class of in situ wavelength selective, tunable, and switchable thermal sources.
Progress toward a self-consistent set of 1D ignition capsule metrics in ICF
Authors: Lindl J. D. , Haan S. W. , Landen O. L. , Christopherson A. R. , Betti R.
Published: December 2018

One-dimensional metrics can be considered an upper bound on the performance that can be achieved given an implosion with an imploding mass Mimp and a given adiabat α, driven to an implosion velocity V by a specified ablation pressure Pa for single shell capsules with low-opacity ablators. The quantitative value of an ignition metric depends on the definition of ignition. We review the choices that have been made by various authors before settling on a definition based on yield amplification of 30 where yield amplification is the ratio of the yield from an implosion that includes the alpha particle and neutron deposition relative to the yield obtained from PdV work alone. We then derive improved 1D ignition metrics for radiation-driven inertial confinement fusion targets that span a wide range of drive pressures, adiabats, and scales. This includes emphasizing the importance of the total imploding mass and kinetic energy inside the ablation front, including the remaining ablator mass and kinetic energy, on the 1D ignition metrics. We have also explicitly included the sensitivity to ablation pressure driving the implosion, as well as the sensitivity to the coupling efficiency between the total incoming kinetic energy and the hot spot. For implosions in which the remaining ablator mass contributes to the total stagnated mass, we have developed an approach based on defining an effective implosion adiabat which incorporates the properties and the mass of the stagnated ablator as well as the cold DT fuel. We have added a dependence on total ρr to account for the fact that the time available for self-heating increases as the total ρr increases. This extends previous work in that the value of the product of stagnation pressure times burn width required for ignition depends on the total ρr as well as on the fuel ion temperature. Additionally, we show that ignition metrics derived from a requirement on the product of the hotspot ρr and the hot spot temperature are equivalent to ignition metrics derived from a requirement on the product of stagnation pressure and burn width. Further, we discuss those ignition metrics, developed as metrics for the underlying hydrodynamics in the absence of alpha heating, which can be used when alpha heating is present.
Analysis of thermophysical characteristic of SiO2/water nanofluid and heat transfer enhancement with field synergy principle
Authors: Yan Suying , Zhang Huiying , Wang Feng , Ma Rui , Wu Yuting , Tian Rui
Published: December 2018

Nanofluid is one of the most popular and promising heat-transfer fluids. SiO2/water nanofluid suspension stability and their thermophysical characteristics were investigated. Specifically, the suspension stability of the nanofluid was characterized using a Malvern Zetasizer Nano Instrument. The thermal conductivity of the nanofluid was studied at different temperatures and particle sizes. The results indicated that the thermal conductivity of the nanofluid with a mass fraction of 5% increased to 6.8% compared with the water based fluid. Meanwhile, the mean field synergy angle of the spiral microchannel radiator with different properties of the nanofluid was simulated based on different structure microchannel sizes to evaluate the heat transfer performance according to the velocity and the temperature field. The results indicated that the mean field synergy angle was proportional to the nanoparticle size while inversely to the mass fraction of the nanofluid, and their strengthening heat transfer effect was enhanced. The structure size of the microchannel was one of the important effect factors on the mean field synergy angle.
Intravascular tri-modality system: Combined ultrasound, photoacoustic, and elasticity imaging
Authors: Wang Pingping , Chen Zhongjiang , Yang Fen , Yang Sihua , Xing Da
Published: December 2018

We have developed a hybrid intravascular imaging system for the early detection of vulnerable plaque by combining three complementary imaging techniques: ultrasound imaging (USI), photoacoustic imaging (PAI), and photoacoustic elasticity imaging (PEI). As a loading-free elasticity detection method, PEI can quantitatively obtain the tissue elasticity through the photoacoustic phase. By sharing the same ultrasound detection system, USI and PAI could be organically combined. Meanwhile, the optical absorption and elasticity images of plaque are simultaneously reconstructed by the same photoacoustic pulses. To prove the imaging capabilities and complementarity of the system, mimicking phantom experiments were conducted. Furthermore, ex-vivo experiments were performed on the rabbit abdominal aorta to achieve an early assessment of atherosclerosis by detecting the presence and the development extent of lipid plaques. The results illustrate that the system can simultaneously detect the structural composition and the mechanical properties of plaque, thereby showing great potential for accurately diagnosing the atherosclerosis.
Nonlinear optics in carbon nanotube, graphene, and related 2D materials
Authors: Yamashita Shinji
Published: December 2018

One- and two-dimensional forms of carbon, carbon nanotube, and graphene, and related 2D materials, have attracted great attention of researchers in many fields for their interesting and useful electrical, optical, chemical, and mechanical properties. In this tutorial, we will introduce the basic physics and the linear optical properties of these 1D/2D materials. We then focus on their nonlinear optical properties, saturable absorption, electro-optic effect, and nonlinear Kerr effect. We will also review and discuss a few key applications using the ultrafast nonlinear phenomena possessed by these 1D/2D materials: (1) short-pulse fiber lasers using saturable absorption, (2) electro-optic modulators, and (3) all-optical signal processing devices.
Strain engineering in functional 2-dimensional materials
Authors: Sun Yufei , Liu Kai
Published: December 2018

Two-dimensional (2D) materials have attracted growing interest in the past decade because of their extraordinary properties and great potential in a wide range of applications. Strain is regarded as a simple yet powerful tool to modulate the properties of 2D materials, as it directly affects lattice structures and thus alters electronic structures. In this tutorial, we first discuss the fundamentals of strain engineering in 2D materials from macro and atomic perspective and then review some approaches to strain engineering as well as their merits and drawbacks. After that, we examine in detail how strain modulates physical and chemical properties in various types of 2D materials. In the last section of this tutorial, the applications of strain engineering in functional 2D materials are exhibited.
Unraveling bulk and grain boundary electrical properties in La0.8Sr0.2Mn1−yO3±δ thin films
Authors: Chiabrera Francesco , Garbayo Iñigo , Pla Dolors , Burriel Mónica , Wilhelm Fabrice , Rogalev Andrei , Núñez Marc , Morata Alex , Tarancón Albert
Published: December 2018

Grain boundaries in Sr-doped LaMnO3±δ thin films have been shown to strongly influence the electronic and oxygen mass transport properties, being able to profoundly modify the nature of the material. The unique behavior of the grain boundaries can be correlated with substantial modifications of the cation concentration at the interfaces, which can be tuned by changing the overall cationic ratio in the films. In this work, we study the electronic properties of La0.8Sr0.2Mn1−yO3±δ thin films with variable Mn content. The influence of the cationic composition on the grain boundary and grain bulk electronic properties is elucidated by studying the manganese valence state evolution using spectroscopy techniques and by confronting the electronic properties of epitaxial and polycrystalline films. Substantial differences in the electronic conduction mechanism are found in the presence of grain boundaries and depending on the manganese content. Moreover, the unique defect chemistry of the nanomaterial is elucidated by measuring the electrical resistance of the thin films as a function of oxygen partial pressure, disclosing the importance of the cationic local non-stoichiometry on the thin film behavior.
Hole transport in selenium semiconductors using density functional theory and bulk Monte Carlo
Authors: Mukherjee Atreyo , Vasileska Dragica , Goldan A. H.
Published: December 2018

Amorphous selenium is emerging as a viable large-area imaging detector with avalanche multiplication gain for low-light and low-dose radiation detection applications. A key feature of its avalanche process is that only holes become “hot” carriers and undergo impact ionization. Thus, understanding the transport of non-equilibrium hot holes in extended states is pivotal to all the device applications. One of the interesting aspects of elemental selenium is the similar general feature of the electronic structure for various phase modifications. This stems from the strikingly similar short-range order between the crystalline and amorphous phases of selenium. At high electric fields, hole mobility in amorphous selenium loses its activated behavior and saturates with transport shifted entirely from localized to extended states. Thus, we expect the general details of the extended-state hole-phonon interaction in the amorphous phase to be described by the band-transport lattice theory of its crystalline counterparts, namely, monoclinic and trigonal selenium. To that effect and due to the intrinsic meta-stability of the monoclinic phase and high trap density in prepared specimens, we study hole transport in crystalline trigonal selenium semiconductors using a bulk Monte Carlo technique to solve the semi-classical Boltzmann transport equation. We validated our transport model by showing the excellent match between experimentally calculated hole drift mobilities with that calculated using the bulk Monte Carlo technique. Furthermore, calculations of the field-dependent carrier energy showed that holes in selenium can break the thermal equilibrium and get hot at which point the rate of energy gain from the applied electric field exceeds that of energy loss from the lattice.
Solution processed copper tetrabenzotriazaporphyrin films for organic field effect transistors
Authors: Chaure Nandu B. , Cammidge Andrew N. , Chambrier Isabelle , Ray Asim K.
Published: December 2018

Experimental characteristics of bottom-gate-contact organic thin film field-effect transistors (OTFTs) with 70 nm thick films of solution processed non-peripherally octahexyl-substituted copper tetrabenzotriazaporphyrin (6CuTBTAP) novel asymmetric molecules as active layers on silicon substrates are analyzed by both linear and non-linear parameter extraction methods in order to examine the field-dependent mobility and contact effects. Both linear and saturation field effect mobilities of OTFTs have been computationally determined as a function of gate voltage in the presence of the contact resistances. The Poole-Frankel mechanism is found to be responsible for charge transport during the saturation regime, giving the highest mobility of 6.9 × 10−2 cm2 V−1 s−1 at the gate-source voltage (VG) of 50 V. The on-off ratio is found to be 106. The contact resistance at the interface between gold electrodes and the 6CuTBTAP active layer decreases with VG sharply from 75 MΩ corresponding to VG = 0 V to 10 MΩ once the transistor is turned on at the threshold voltage.
Novel phases in ammonia-water mixtures under pressure
Authors: Naden Robinson Victor , Marqués Miriam , Wang Yanchao , Ma Yanming , Hermann Andreas
Published: December 2018

While ammonia and water readily form hydrogen-bonded molecular mixtures at ambient conditions, their miscibility under pressure is not well understood, yet crucial to model the interior of icy planets. We report here on the behavior of ammonia-water mixtures under extreme pressure conditions, based on first-principles calculations of 15 stoichiometries in the pressure range of 1 atm–10 Mbar. We show that compression facilitates proton transfer from water to ammonia in all relevant mixtures. This favors ammonia-rich hydrates above 1 Mbar, stabilized by complete de-protonation of water and the formation of the unusual structural motifs O2−⋅(NH4+)2 and O2−⋅(N2H7+)2. The hydronitrogen cations persist to the highest pressures studied. We predict a new ammonia-rich 4:1-hydrate at intermediate pressures and find that by 5.5 Mbar, close to the core-mantle boundary of Neptune, all cold ammonia-water mixtures are unstable against decomposition into their constituents.
Electronic and optical properties of bilayer SnS with different stacking orders: A first principles study
Authors: Zhang J. , Lang X. Y. , Jiang Q.
Published: December 2018

Two-dimensional materials with tunable optical and electronic properties offer many interesting opportunities for optoelectronic devices and solar cells. Here, we report different stacking orders as an effective approach to tune the electronic and optical properties of SnS bilayers. Using the first principles density functional theory, the bandgap of the SnS bilayers is demonstrated to vary from 1.20 to 1.36 eV due to different stacking orders, wherein the AB-stacked SnS bilayer has a direct bandgap, different from AA- and AC-stacked ones. Furthermore, these SnS bilayer structures exhibit a strong light absorption over a wide range (∼1 to 6 eV), showing genuine potential for optoelectronic applications. When a MoS2 monolayer is combined with a p-type AB-stacked SnS bilayer, or a WS2 monolayer plus any of the above three stacking structures, the trilayer structures can be effective solar cell materials with a type-II heterojunction alignment.
Short-term memory in electric double-layer capacitors
Authors: Allagui Anis , Zhang Di , Elwakil Ahmed S.
Published: December 2018

Shared by various physical, chemical, and biological systems, fractional-order dynamics assert that the present state of a system is the result of not only the applied stimulus but also its past history. Consequently, in fractional-order systems, there exists a system-specific, input-dependent memory kernel. In this study, we demonstrate experimentally the existence of a memory effect in electric double-layer capacitors which are known to exhibit a fractional-order behavior through their non-single, distributed internal time constants. This is performed by showing variance in the discharge patterns of the device into a constant resistor after being charged to the same steady-state voltage and steady-state electric charge, first by using a step voltage and then using a linear voltage sweep. We observe a short-term memory effect in the transient regime which eventually fades out with time. This was attributed to the input-modulated device impedance and was confirmed mathematically.
Productivity increase, reduction of nitrogen fertiliser use and drought-stress mitigation by inoculation of Marandu grass (Urochloa brizantha) with Azospirillum brasilense
Authors: Leite Rubson da C. , dos Santos José G. D. , Silva Eduardo L. , Alves Cássio R. C. R. , Hungria Mariangela , Leite Robson da C. , dos Santos Antonio C.
Published: December 2018

Among the forage species cultivated in South America, the genus Urochloa is the most used, and the cultivar Marandu of U. brizantha is the most widely planted in Brazil. The objective of this study was to evaluate forage performance in association with Azospirillum brasilense, combined with nitrogen (N) fertilisation. The study was conducted under field conditions in Araguaína, Tocantins, in the central region of Brazil, between March 2016 and March 2017. Four N fertiliser rates (0, 12.5, 25 and 50kg/ha of N per cutting cycle) were combined with two inoculation treatments (inoculated and non-inoculated), with evaluations carried out in three periods of the year (transition, dry and wet seasons). Marandu grass plants inoculated with A. brasilense had greater plant height, number of tillers and forage production than non-inoculated plants, regardless of the N rate. Inoculation with A. brasilense allowed a 20% reduction in N fertilisation. Our results indicate that inoculation with A. brasilense in Marandu grass, as well as increasing forage production, can help to mitigate the stresses caused by the dry season.
Bovine gonadotrophs express anti-Müllerian hormone (AMH): comparison of AMH mRNA and protein expression levels between old Holsteins and young and old Japanese Black females
Authors: Kereilwe Onalenna , Kadokawa Hiroya
Published: December 2018

Anti-Müllerian hormone (AMH) is secreted from ovaries and stimulates gonadotrophin secretion from bovine gonadotroph cells. Other important hormones for endocrinological gonadotroph regulation (e.g. gonadotrophin-releasing hormone, inhibin and activin) have paracrine and autocrine roles. Therefore, in this study, AMH expression in bovine gonadotroph cells and the relationships between AMH expression in the bovine anterior pituitary (AP) and oestrous stage, age and breed were evaluated. AMH mRNA expression was detected in APs of postpubertal heifers (26 months old) by reverse transcription-polymerase chain reaction. Based on western blotting using an antibody to mature C-terminal AMH, AMH protein expression was detected in APs. Immunofluorescence microscopy utilising the same antibody indicated that AMH is expressed in gonadotrophs. The expression of AMH mRNA and protein in APs did not differ between oestrous phases (P>0.1). We compared expression levels between old Holsteins (79.2±10.3 months old) and young (25.9±0.6 months old) and old Japanese Black females (89.7±20.3 months old). The APs of old Holsteins exhibited lower AMH mRNA levels (P<0.05) but higher AMH protein levels than those of young Japanese Black females (P<0.05). In conclusion, bovine gonadotrophs express AMH and this AMH expression may be breed-dependent.
When actions and looks don’t line up
Authors: Contemori Carla , Pozzan Lucia , Galinsky Phillip , Dussias Paola E.
Published: December 2018

In two eye tracking experiments, we investigate how adult child-L2 speakers of English resolve prepositional phrase (PP) attachment ambiguity in their dominant language (English), and whether they use prosodic information to aid in the process of garden-path recovery. The findings showed an increased processing cost associated with the revision of temporary ambiguous sentences for the child-L2 adults relative to the native English speakers. When prosody was informative, the child-L2 adults were able to use prosodic information to guide the interpretation of their later acquired, dominant language. However, they performed revision significantly less successfully than the native speakers. Although processing was similar for the native English speakers and the adult child-L2 speakers of English, when it comes to sensitivity to prosodic information and referential context, the two groups differed with regards to reanalysis both in the presence and absence of salient prosodic and referential information.
Inducible down-regulation of MHC class I results in natural killer cell tolerance
Authors: Bern Michael D. , Parikh Bijal A. , Yang Liping , Beckman Diana L. , Poursine-Laurent Jennifer , Yokoyama Wayne M.
Published: December 2018

Natural killer (NK) cells are innate lymphocytes that are thought to kill cells that down-regulate MHC class I (MHC-I) through “missing-self” recognition. NK cells from B2m−/− mice that lack surface MHC-I, however, are not autoreactive as predicted by the missing-self hypothesis. As a result, it is unclear if MHC-I down-regulation in vivo induces NK cell reactivity or tolerance to missing-self. Here, we generated a floxed B2m mouse to acutely down-regulate MHC-I in vivo in a host that normally expresses MHC-I. Global down-regulation of MHC-I induced NK cell hyporesponsiveness and tolerance to missing-self without overt missing-self reactivity. In contrast, down-regulation of MHC-I on a small fraction of hematopoietic cells triggered missing-self reactivity. Surprisingly, down-regulation of MHC-I only on CD4+ T cells predominately induced tolerance to missing-self without resetting NK cell responsiveness. In this setting, inflammation triggered substantial missing-self reactivity. These results show that MHC-I down-regulation can induce either NK cell tolerance or killing in vivo and that inflammation promotes missing-self reactivity.
Improved results on the oscillation of the modulus of the Rudin-Shapiro polynomials on the unit circle
Authors: Erdélyi Tamás
Published: December 2018

Let

R
k

(
t
)
:=

|

P
k

(

e

i
t

)

|

2

R_k(t) := |P_k(e^{it})|^2

and

S
k

(
t
)
:=

|

Q
k

(

e

i
t

)

|

2

S_k(t) := |Q_k(e^{it})|^2

, where

P
k

P_k

and

Q
k

Q_k

are the usual Rudin-Shapiro polynomials of degree

n
−
1

n-1

with

n
=

2
k

n=2^k

. In a recent paper we combined close to sharp upper bounds for the modulus of the autocorrelation coefficients of the Rudin-Shapiro polynomials with a deep theorem of Littlewood to prove that there is an absolute constant

A
>
0

A>0

such that the equations

R
k

(
t
)
=
(
1
+
η
)
n

R_k(t) = (1+\eta )n

and

S
k

(
t
)
=
(
1
+
η
)
n

S_k(t) = (1+\eta )n

have at least

A

n

0.5394282

An^{0.5394282}

distinct solutions in

[
0
,
2
π
)

[0,2\pi )

whenever

η
\eta

is real,

|

η

|

>

2

−
8

|\eta | > 2^{-8}

, and

k
k

is sufficiently large. In this paper we show that the equations

R
k

(
t
)
=
(
1
+
η
)
n

R_k(t)=(1+\eta )n

and

S
k

(
t
)
=
(
1
+
η
)
n

S_k(t)=(1+\eta )n

have at least

(
1

/

2
−

|

η

|

−
ε
)
n

/

2

(1/2-|\eta |-\varepsilon )n/2

distinct solutions in

[
0
,
2
π
)

[0,2\pi )

for every

η
∈
(
−
1

/

2
,
1

/

2
)

\eta \in (-1/2,1/2)

,

ε
>
0

\varepsilon > 0

, and sufficiently large be

k
≥

k

η
,
ε

k \geq k_{\eta ,\varepsilon }

.
Associations of Hearing Loss and Depressive Symptoms With Incident Disability in Older Adults: Health, Aging, and Body Composition Study
Authors: Armstrong Nicole M , Deal Jennifer A , Betz Joshua , Kritchevsky Stephen , Pratt Sheila , Harris Tamara , Barry Lisa C , Simonsick Eleanor M , Lin Frank R
Published: December 2018

Background

Depressive symptoms and hearing loss (HL) are independently associated with increased risk of incident disability; whether the increased risk is additive is unclear.

Methods

Cox Proportional Hazards models were used to assess joint associations of HL (normal, mild, moderate/severe) and late-life depressive symptoms (defined by a score of ≥8 on the 10-item Center for Epidemiologic Studies-Depression scale) with onset of mobility disability (a lot of difficulty or inability to walk ¼ mile and/or climb 10 steps) and any disability in activities of daily living (ADL), among 2,196 participants of the Health, Aging and Body Composition Study, a cohort of well-functioning older adults aged 70–79 years. Models were adjusted for age, race, sex, education, diabetes, hypertension, and body mass index.

Results

Relative to participants with normal hearing and without depressive symptoms, participants without depressive symptoms who had mild or moderate/severe HL had increased risk of incident mobility and ADL disability (hazard ratio [HR] for mobility disability, mild HL:1.34, 95% confidence interval [CI]: 1.09, 1.64 and HR for mobility disability, moderate/severe HL: 1.37, 95% CI: 1.08, 1.75 and HR for ADL disability, mild HL: 1.32, 95% CI: 1.08, 1.63, and HR for ADL disability, moderate/severe HL: 1.42, 95% CI: 1.11, 1.82). Among participants with depressive symptoms, mild HL (HR: 1.71, 95% CI: 1.09, 2.70) was associated with increased risk of incident mobility disability.

Conclusions

Independent of depressive symptoms, risk of incident disability was greater in older adults with HL, regardless of severity. Further research into HL interventions may delay disability onset.
Survey of cow-calf producer perspectives on management strategies and industry challenges. Part 1: handling practices, and health and industry challenges
Authors: Martin Miriam S , Grau Scott A , Rutherford Burt W , Grandin Temple , Edwards-Callaway Lily N
Published: December 2018

The objectives of this study were to benchmark cow-calf producer perspectives on management strategies and challenges, and to determine if demographic differences and Beef Quality Assurance (BQA) certification status influenced the frequency of certain management strategies. A total of 1,414 responses from cow-calf producers in 44 states were collected through an online survey conducted in partnership with BEEF, a producer-focused magazine. Survey recipients were asked 30 questions to gather demographic information, respondents’ current handling and health management practices, and how they prioritized industry challenges. The frequency of management methods and decisions such as preconditioning and identification methods were impacted by respondent age, operation size, location, and BQA certification (Ps ≤ 0.009). BQA-certified respondents more frequently used electronic ear tags and freeze branding (Ps = 0.009). Overall, 74.5% of respondents were preconditioning their calves. Respondents who were BQA certified more frequently preconditioned their calves (449; 81.5%) compared with those who were not BQA certified (582; 70.4%) (P < 0.001). BQA training seems to be having a positive impact on production practices. Respondents identified cow-calf health as the biggest beef industry challenge and identified land availability or price as the biggest challenge to producers’ own operation. Respondents identified bovine respiratory disease, flies, pinkeye, and reproductive health as the most important animal health issues on producers’ operations. Health challenge responses varied significantly by producer age, beef cow inventory, and region of the United States (Ps < 0.001). Calf or neonate health was most commonly identified as the biggest challenge for respondents under the age of 30 years. Producers between the ages of 55 and 70 years most commonly responded that the Veterinary Feed Directive or regulations were more of a challenge than other age groups. Respondents clearly identified managing herd health as a challenge throughout the survey. Respondents with similar herd health challenges were identified based on demographic categorization, such as age of respondent and region.