bluuebunny/crossref_metadata_2025 huggingface dataset:
Wheelset/rail geometric characteristics and contact forces assessment with regard to wheelset rolling
Authors: Gerlici Juraj , Lack Tomáš
Published: January 2019

The geometric relation between a wheelset and a rail is assessed with the help of geometric characteristics. Geometric characteristics are: equivalent conicity function, delta r function placement of contact points of a wheelset and a rail, tangent gamma function and effective conicity. It turned out that these characteristics are at present the most important not only for the judgment of ride characteristics of a vehicle on the rail but also for the wearing of wheel treads and rail heads, e. i., for the assessment of the track and vehicles in order to find out the current state and for the assessment of changes of the wheels and rails profile shapes in order to improve the current state too. The process of geometric characteristic assessment of a wheelset and rail with regard to wheelset rolling, as well as contact forces are analysed in the article.
Self-propelled inspection vehicle on omni wheels
Authors: Selech Jarosław , Ulbrich Dariusz , Włodarczyk Konrad , Staszak Żaneta , Marcinkiewicz Jacek , Romek Dawid , Wietrzych Patryk
Published: January 2019

In the article design of a self-propelled vehicle for inspecting ventilation ducts and ceiling structures in buildings equipped with omni wheels was presented. Such vehicles are used in places that are hard to reach for people. The vehicle was designed using the vehicle control system – ARDUINO. For this system dedicated program was written, which is used to operate it. The vehicle is remotely controlled by radio waves. Its range is about 100 meters and the power supply is a 12 V battery. The vehicle operator has joysticks (controllers) modelled on those used in game controllers that are used for precise vehicle control. The vehicle is equipped with cameras that allow to view the image in real time. The omni wheels have also been tested for strength by the finite element method (FEM). Carried out FEM analysis as part of the work allowed to determine the strength of omni wheels on the acting forces during vehicle movement.
Conversion of data from the laser scanner to the Ansys Workbench
Authors: Štalmach Ondrej , Sapietová Alžbeta , Dekýš Vladimír , Šulka Peter , Gajdoš Lukáš
Published: January 2019

This paper deals with the data processing in the form of a cloud of points scanned using a handheld 3D laser scanner. The aim of this paper is to use this data to create a representative FEM model and compare two different approaches while one of them involves creating a CAD model and the other one not. The data processing is carried out in the freeware systems MeshLab and Meshmixer and FEM analysis in the software ANSYS Workbench.
Computer evaluation of the influence of liquid metal movements on defects formation in the casting
Authors: Sowa Leszek , Skrzypczak Tomasz , Kwiatoń Paweł
Published: January 2019

This paper concerns the modelling of the solidification process including the phenomena of heat transfer and fluid flow during the initial stage of the metal casting process. During this period, the molten metal motions have an essential influence on solidification kinetics. An analysis of solidification kinetics, by determining the velocity and temperature fields in a system of riser-casting was made. Velocity fields were obtained by solving the momentum equations and the continuity equation, while the thermal fields were obtained by solving the conduction equation containing the convection term. After completion of the filling process the main solidification of molten metal takes place and its shrinkage. The phenomenon of casting shrinkage cannot be avoided, but it is possible to minimize its negative effects on the casting quality. One with ways to solve this problem is to design the mould in such a way that the solidification proceeds in accordance to the assumed direction and finished in the riser. Generally, the aim of search is to obtain a casting without shrinkage defects.
Evaluation of the possibility of using the Drucker-Prager-Cap model in simulations of the densification process of shredded natural materials
Authors: Berdychowski Maciej , Talaśka Krzysztof , Wilczyński Dominik
Published: January 2019

The article presents the preliminary results of numerical simulations of the densification process of shredded waste wood. The purpose of the simulation was to evaluate the possibility of using the Drucker-Prager-Cap model in the field of modeling plastic deformation of shredded biomaterials. The experimental studies allowed the verification of numerical simulations. In the research, the stamp-cylinder assembly of a special construction was used, adapted for assembly on a strength machine. The tests carried out are to constitute guidelines for the construction of machinery and devices for compacting biomass.
Flexible grippers for industrial robots – comparison of features of low-cost 3D printed component
Authors: Zbroja Piotr , Szykiedans Ksawery , Credo Wojciech
Published: January 2019

The aim of presented work was to analyse the feasibility of using 3D-print technology in robotics based on the production of industrial robot flexible grippers. For selected geometry of gripper single finger available 3D printing techniques has been analysed. The study made by authors uses the following additive technologies and devices: SLS (Selective laser Sintering) and FDM (Fused deposition modelling). As a prior an analyses of capabilities of individual technologies were done by testing the quality of the 3D CAD model recreated on test print-outs. Based on the printed gripper, its functionality, and strength properties were examined. Strength of grapplers was tested with a use of an MTS test machine under repeating deflexion simulating standard operational cycle of a gripper. Test proved that at least few thousands of cycle are possible to be made by a 3D printed gripper. What interesting gripper made with use of the less advanced printer showed different wear behaviour than an one made on the more advanced. First one showed almost instantaneous start of slow and constant strength degradation while the second one proved to have a stable deflexional capability by almost twice an number of cycles. More isotropic structure of an SLS printed gripper caused the best results of all tested ones.
Investigation of strength conditions of the new wagon prototype type Zans
Authors: Šťastniak Pavol , Moravčík Marián , Smetanka Lukáš
Published: January 2019

The paper describe the most significant and innovative research and development design solutions and computational procedures as part of European structural funds project. The object of our calculations is strength simulation analyzes of a new structure of railway tank wagon for transportation of ignition matters through FEM analysis created in program MSC.Marc. Results of calculations and prototype tests prove, that new structure of the construction satisfies strength assessments according to valid requirements and standards.
Road train motion stability in BRT system
Authors: Sakhno Vladimir , Gerlici Juraj , Poliakov Viktor , Kravchenko Alexandr , Omelnitcky Oleg , Lack Tomas
Published: January 2019

The peculiarities of organization and perspectives of mass passenger transportation in the city and beyond are considered with the use of "Bus Rapid Transport" (BRT) or Metrobus. Different aspects of study of motor vehicles (MV) controllability and stability are analyzed. It is substantiated that it is sufficient to consider the potential stability of the MV itself, in order to guarantee the stability of the "driver MV" system with a large reserve. A mathematical model of a three-axle bus train consisting of a bus and two trains (metrobus) is developed and the factors influencing the critical speed as the main index of the stability of its movement are determined. It is established that the increase of the critical speed of the metrobus can be achieved by increasing the base of the bus, the first and the second trailer, as well as the mass of the bus and the coefficients of resistance of the drive wheels of the bus driving axle and the trailers axles. At the same time, increasing the distance from the mass center to the bus rear axle, increasing the distance from the mass center to the point of the coupling of the bus with the first trailer, increasing the mass of trailers and the resistance of the resistance of the wheel drive of the bus axis lead to a decrease in the critical speed of the metrobus. This must be taken into account both when designing metrobuses, and when operating them.
The determination of the rolling resistance coefficient of a passenger vehicle with the use of selected road tests methods
Authors: Pałasz Bartłomiej , Waluś Konrad J. , Warguła Łukasz
Published: January 2019

Wide range of laboratory and road methods of determining the rolling resistance coefficient impose the need to find an effective way of its estimation. The obtained values of this coefficient differ depending from the assumed calculation model and influence the quality and quantity assessment of cooperation processes between tire and surface. The article presents two experimental methods of determining the rolling resistance coefficient. Road tests were carried out with the use of coast-down and free-rolling method. For each of the road methods the value of the rolling resistance coefficient was determined in three ways. It allowed to compare the selected research methods and calculation methods with the values available in literature.
Detection of composite damage by IR NDT using ultrasonic and optic excitation
Authors: Dekýš Vladimír , Štalmach Ondrej , Soukup Josef , Sapietová Alžbeta , Rychlíková Lenka
Published: January 2019

The submitted paper presents experience with detection of damaged composites by means of an ultrasonic excitation system in comparison with an optic system of excitation. In case of the ultrasonic excitation system is a high-frequency signal modulated by lock-in frequency. For a selection of the carrier signal we measured a response of a sample to sweep excitation and a sample resonance was defined by means of STFT. Consequently, the method lock-in was applied for detection. In case of the optic excitation system we applied several suitably selected frequencies with an aim to obtain information from various depths of the measured object. Results of measurements are presented in composite samples of CFRP.
Dissemination of shock waves in thin isotropic plates
Authors: Klimenda František , Soukup Josef , Žmindák Milan , Skočilasová Blanka
Published: January 2019

The article deals with the propagation of shock waves in thin isotropic plates. The solution is done analytically. The geometric model of Kirchhoff and Rayleigh was used for the solution. Material model was used Hook. The shock wave is induced by the impact of the punch into the centre of the plate. The longitudinal waves propagate in thexandyaxis, the transverse wave propagates in the axis. Comparison of the longitudinal and transverse wave propagation of both models at selected points is made. Comparisons are displacements, velocities and tensions inx, y andzaxis, depending on time. The rectangular plate is made of unidirectional rolled aluminium sheet of high purity. The plate is around the perimeter fixed. The MATLAB program was used to solve this problem.
Prototype of a controllable damper based on granular materials subjected to partial vacuum
Authors: Zalewski Robert , Bartkowski Piotr
Published: January 2019

In the paper a proposal of granular damper prototype has been introduced. The granular damper works on the basis of a core made of Vacuum Packed Particles. Idea of Vacuum Packed Particles consists of placing loose granular grains into a hermetic envelope, wherein in the next stage a partial vacuum is generated. The difference between an atmospheric pressure, externally surrounding the core and internal one, causes occurring friction forces between single grains. Interacting friction forces are greater for higher values of internal underpressure. In presented paper the authors focus on analysis of experimental results obtained for various values of underpressure. Variations in energy dissipation possibilities are particularly described in this paper.
Damping in magnetorheological elastomers under compressive stress
Authors: Kukla Mateusz , Talaśka Krzysztof , Malujda Ireneusz
Published: January 2019

Magnetorheological elastomers are an important area of study in non-classical engineering materials. These are smart materials, in which some of the physical properties are dependent on the applied magnetic field. This unique property allows to suggest new, innovative practical applications. It is therefore relevant to carry out studies in the possible application of magnetorheological elastomers in machine construction. The present article presents the results of study regarding the properties of the discussed materials subject to compressive stresses. Particular attention is given to the observed growth of surface area of mechanical hysteresis loops, which is evidence of the possibility to change the damping properties of magnetorheological elastomers. This property can be utilized in the construction of different types of machines and devices. These mostly applies to energy absorbers such as active vibration absorbers.
Numerical modeling of cutting process of steel sheets using a laser beam
Authors: Saternus Zbigniew , Piekarska Wiesława , Kubiak Marcin , Domański Tomasz , Goszczyńska-Króliszewska Dorota
Published: January 2019

Laser beam cutting technology is becoming increasingly popular in various industries. Advantages of this method is a very high cutting speed and a precision of edges of cut elements. Good quality depends on many technological parameters. Numerical prediction of the effect of cutting process parameters on the quality of the surface can be useful for technologists. The work concerns the numerical analysis of the laser cutting process of sheet made of steel. The influence of selected parameters on the energy efficiency of the heat source and the cutting speed are analyzed. Numerical calculations are performed in Abaqus software. Three-dimensional discrete model of the analyzed system is developed. The standard material parameters of austenitic steel changing with the temperature are taken into account. Gauss model describing the distribution of movable heat source of a laser beam power are assumed in the solution algorithms. The influence of various parameters of the laser beam on obtained temperature field and shape of cut zone is estimated on the basis of numerical calculations. The results are compared with the results of the experiment.
Optical windows as materials for high-speed shock wave detectors
Authors: Bhowmick Mithun , Basset Will P. , Matveev Sergey , Salvati Lawrence , Dlott Dana D.
Published: January 2019

Experimental studies of high-velocity (1-4 km/s) impacts of laser-launched flyer plates with polycrystalline, glassy or polymer windows were performed, with the intent of understanding and assessing the use of optical windows as high-speed solid-state shock wave detector materials. The problem is that the detector material undergoes radical physical transformations during the measurement. Here we present a simplified model where the detector material transformations are described as velocity and time dependent changes in shock impedance. The window materials were used to study the detonation shock produced by nitromethane, which is about 20 GPa and 10 ns. Reference experiments producing shocks in this pressure and duration range characterized how the shock impedances changed with impact velocity and shock duration. Sapphire, CaF2 and LiF windows had the fastest response to the detonation shocks, while the polymer windows had a sluggish response. Pyrex and BK7 were the best of the glassy windows.
Low-loss fiber-to-chip couplers with ultrawide optical bandwidth
Authors: Gehring H. , Blaicher M. , Hartmann W. , Varytis P. , Busch K. , Wegener M. , Pernice W. H. P.
Published: January 2019

Providing efficient access from optical fibers to on-chip photonic systems is a key challenge for integrated optics. In general, current solutions allow either narrowband out-of-plane-coupling to a large number of devices or broadband edge-coupling to a limited number of devices. Here we present a hybrid approach using 3D direct laser writing, merging the advantages of both concepts and enabling broadband and low-loss coupling to waveguide devices from the top. In the telecom wavelength regime, we demonstrate a coupling loss of less than −1.8 dB between 1480 nm and 1620 nm. In the wavelength range between 730 nm and 1700 nm, we achieve coupling efficiency well above −8 dB which is sufficient for a range of broadband applications spanning more than an octave. The 3D couplers allow relaxed mechanical alignment with respect to optical fibers, with −1 dB alignment tolerance of about 5 µm in x- and y-directions and −1 dB alignment tolerance in the z-direction of 34 µm. Using automatized alignment, many such couplers can be connected to integrated photonic circuits for rapid prototyping and hybrid integration.
Single-layer ferromagnetic and piezoelectric CoAsS with pentagonal structure
Authors: Liu Lei , Zhuang Houlong L.
Published: January 2019

Single-layer pentagonal materials are an emerging family of two-dimensional (2D) materials that could exhibit novel properties due to the building blocks being pentagons instead of hexagons as in numerous 2D materials. Based on our recently predicted single-layer pentagonal CoS2 that is an antiferromagnetic (AFM) semiconductor, we replace two S atoms by As atoms in a unit cell to form single-layer pentagonal CoAsS. The resulting single-layer material is dynamically stable according to the phonon calculations. We find two drastic changes in the properties of single-layer pentagonal CoAsS in comparison with those of CoS2. First, we find a magnetic transition from the AFM to FM ordering. We understand that the transition is caused by the lower electronegativity of As atoms, leading to the weakened bridging roles on the superexchange interactions between Co ions. Single-layer pentagonal CoAsS also shows significantly stronger magnetocrystalline anisotropy energy due to stronger spin-orbit coupling. We additionally perform Monte Carlo simulations to calculate the Curie temperature of single-layer pentagonal CoAsS and the predicted Curie temperature is 95 K. Second, we find that single-layer pentagonal CoAsS exhibits piezoelectricity, which is absent in single-layer pentagonal CoS2 due to its center of symmetry. The computed piezoelectric coefficients are also sizable. The rare coexistence of FM ordering and piezoelectricity makes single-layer pentagonal CoAsS a promising multifunctional 2D material.
Unexpected chemistry from the homogeneous thermal decomposition of acetylene: An ab initio study
Authors: Wang En-dong , Li Guang-yue , Ding Jun-xia , He Guo-zhong
Published: January 2019

The formation of the aromatic ring during the formation of polycyclic aromatic hydrocarbons (PAHs) remains controversial and the experimental evidence is still lacking. Moreover, the formation mechanism of benzene from acetylene in the gas phase has also puzzled organic chemists for decades. Here, ab initio molecular dynamics simulations and electronic structure calculations provide compelling evidence for an unexpected competitive reaction pathway in which the aromatic ring is formed through successive additions of vinylidene. Moreover, no collisions cause bond dissociation of the acetylene molecule during the formation of benzene in this work. This study reveals the key role for the vinylidene carbene and determines the lifetime of vinylidene.
Direct observation of transition metal dichalcogenides in liquid with scanning tunneling microscopy
Authors: Wang Ze , Wang Ji-hao , Ge Wei-feng , Meng Wen-jie , Zhang Jing , Feng Qi-yuan , Hou Yu-bin , Lu Qing-you
Published: January 2019

We present atomic-resolution images of TiSe2, MoTe2 and TaS2 single crystals in liquid condition using our home-built scanning tunneling microscopy (STM). By facilely cleaving of single crystals in liquid, we were able to keep the fresh surface not oxidized within a few hours. Using the high-stable home-built STM, we have obtained atomic resolution images of TiSe2 accompanied with the single atom defects as well as the triangle defects in solution for the first time. Besides, the superstructure of MoTe2 and hexagonal charge-density wave domain structure in nearly commensurate phase of TaS2 were also obtained at room temperature (295 K). Our results provide a more efficient method in investigating the lively surface of transition metal dichalcogenides. Besides, the high stable liquid-phase STM will support the further investigations in liquid-phase catalysis or electrochemistry.
Electrosynthesis of CuO nanocrystal array as a highly efficient and stable electrocatalyst for oxygen evolution reaction
Authors: Xiong Wei-lin , Abdullah Muhammad Imran , Ma Ming-ming
Published: January 2019

Electrodeposition of active catalysts on electrodes appears as a convenient approach to prepare non-noble-metal based electrocatalysts with defined micro- and nano-structures. Herein we report a new strategy of fabricating a 3-D hierarchical CuO nanocrystal array (CuO NCA) on Cu foam through a two-step sacrifice-template method. This CuO NCA possesses high conductivity, great stability, and impressive catalytic activity for oxygen evolution reaction (OER) in alkaline electrolytes. The CuO NCA can achieve a high current density of 100 mA/cm2 at a relatively low overpotential of 400 mV for OER, which shows a better performance than other Cu-based OER catalysts and IrO2. The high activity of CuO NCA is well retained during a 10-h OER test at a high current density around 270 mA/cm2, which is about 10 times higher than the current density achieved by IrO2 (around 25 mA/cm2) with the same applied overpotential. According to our best knowledge, CuO NCA is currently the most efficient and stable Cu-based electrocatalyst for water oxidation in alkaline electrolytes.
Ultraviolet optical properties and structural characteristics of radio frequency-deposited HfO2 thin films
Authors: Sun Cun-zhi , Hong Rong-dun , Chen Xia-ping , Cai Jia-fa , Wu Zheng-yun
Published: January 2019

Hafnium oxide (HfO2) thin films were deposited on quartz substrate by radio frequency magnetron sputtering with power from 160 W to 240 W. The optical and microstructural properties of samples before and after annealing were characterized by XRD, XPS, UV-VIS-NIR spectrophotometer and ellipsometer. The results show optical transmittances with low absorption in wavelength range above λ=200 nm for all samples. The appropriate annealing can transfer the amorphous state of as-deposited films to the crystal film, contribute to the growth of nanocrystalline and compressive stress, optimize the stoichiometry of the film and systematically improve film density and the refractive index. In consideration of the stability of proper refractive index (>2) and high optical transmittance in UV band, HfO2 films deposited approximately at 220 W can be used in UV anti-reflection system.
Energy-transfer processes of Xe (6p[1/2], 6p[3/2]2, and 6p[5/2]2) atoms under the condition of ultrahigh pumped power
Authors: He Shan , Chu Jun-zhi , Liu Dong , Li Xue-yang , Guo Jing-wei , Liu Jin-bo , Hu Shu , Li Hui , Wang Peng-yuan , Chen Ying , Sang Feng-ting , Jin Yu-qi
Published: January 2019

The kinetic processes of Xe (6p[1/2]0, 6p[3/2]2, and 6p[5/2]2) atoms under the focused condition were investigated. The atomic density of the laser prepared state significantly increases. Therefore, the probability of the energy-pooling between two high-lying atoms increases. There are three major types of the energy-pooling collisions. The first type is the energy-pooling ionization. Once the excitation laser is focused, the obvious ionization can be observed from the side window whenever the laser prepared state is 6p[1/2]0, 6p[3/2]2, or 6p[5/2]2 state. Ionization of Xe is attributed to the energy-pooling ionization or a Xe* atom reabsorbing another excitation photon. The second type is energy-pooling with big energy difference. When the 6p[1/2]0 state is the laser prepared state, the energy-pooling collision between two 6p[1/2]0 atoms can produce one 5d[3/2]1 atom and one 6s′[1/2]0 atom. The third type is energy-pooling with small energy difference. The intensities of fluorescence lines are much stronger that five secondary 6p states act as the upper states, and the rising edges of these fluorescence lines are much steeper. The primary mechanism of generating the secondary 6p atoms is energy-pooling collision instead of collision relaxation. Based on the collision probability, the rate of energy-pooling between two 6p[1/2]0 atoms is deduced (6.39 × 108 s−1). In addition, the 6s atoms also increase under the focused condition. Therefore, all the fluorescence lines are serious trailing by radiation trapping.
Intracellular self-assembly of TPE-biotin nanoparticles enables aggregation-induced emission fluorescence for cancer-targeted imaging
Authors: Xu Yi-fei , Jiang Jin-hui
Published: January 2019

Fluorogens with aggregation-induced emission (AIE) characteristics have recently been widely applied for studying biological events, and fluorogens with “smart” properties are especially desirable. Herein, we rationally designed and synthesized a biotinylated and reduction-activatable probe (Cys(StBu)-Lys(biotin)-Lys(TPE)-CBT (1)) with AIE properties for cancer-targeted imaging. The biotinylated probe 1 can be actively uptaken by the biotin receptor-overexpressing cancer cells, and then “smartly” self-assemble into nanoparticles inside cells and turn the fluorescence “On”. Employing this “smart” strategy, we successfully applied probe 1 for cancer-targeted imaging. We envision that this biotinylated intelligent probe 1 might be further developed for cancer-targeted imaging in routine clinical studies in the near future.
Nitrogen increases drought tolerance in maize seedlings
Authors: Song Yushuang , Li Jinlu , Liu Mingli , Meng Zhe , Liu Kaichang , Sui Na
Published: January 2019

Drought and nitrogen availability are two important environmental factors that affect plant growth and the global distribution of plants. We examined the effect of nitrogen on PSII in the leaves of maize seedlings under drought stress using three nitrogen concentrations (0.5, 7.5 and 15mM) and three levels of water availability (normal conditions, mild drought and severe drought). Shoot fresh and dry weights and root fresh weight decreased with increasing drought conditions. In maize leaves subjected to drought stress, the chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, net photosynthetic rate, transpiration rate, stomatal conductance, maximum chemical efficiency (Fv/Fm), and photochemical efficiency of PSII (ΦPSII) were significantly reduced. Moderate nitrogen supply relieved the drought stress and enhanced the photosynthetic capacity. Malondialdehyde, H2O2 and O2−• accumulated in maize leaves under drought stress. Superoxide dismutase and ascorbate peroxidase activities increased in maize leaves under mild drought stress, but were significantly reduced under severe drought stress. The NO3− content and nitrate reductase (NR) activity of maize leaves were significantly reduced under drought stress, while moderate nitrogen supply promoted the accumulation of NO3− and an increase in the nitrate reductase activity. The abscisic acid content increased significantly; this increase was positively correlated with the nitrogen concentration under drought stress. Together, these results indicate that moderate nitrogen supply increases plant resistance to drought stress, while high or low nitrogen concentrations increase the sensitivity of maize to drought stress. These findings are important for guiding the agricultural use of nitrogen fertilisers.
Physiology and metabolism of grafted bell pepper in response to low root-zone temperature
Authors: Aidoo Moses Kwame , Sherman Tal , Lazarovitch Naftali , Fait Aaron , Rachmilevitch Shimon
Published: January 2019

Low temperature is a prominent limiting factor for tropical originated crops production in temperate regions, particularly during cool-season production. The diverse response of two rootstocks (Canon-sensitive and S103-tolerant to low root-zone temperature) was studied when exposed to aeroponically different temperature regimes at the root zone: constant low temperature of 14°C low root-zone temperature (LRZT), transient exposure to LRZT of 27–14−27°C and control temperature of 27°C. Gas exchange, shoot dry mass, and root morphology were measured. Shifts in central and secondary metabolite levels in the leaves and roots were examined by gas chromatography-mass spectrometry (GC-MS). Low root-zone temperature inhibited photosynthesis and transpiration of both grafted bell pepper plants; however, self-grafted Canon physiology was impeded to a greater extent compared with Canon grafted onto rootstock S103. Rootstock S103 demonstrated higher sink potential contributing to milder reduction of photosynthesis and transpiration during stress compared with self-grafted Canon. This reduction of gas exchange led to a significant reduction of root maximum length and root dry mass in self-grafted Canon in response to the stress at 14°C compared with Canon grafted onto rootstock S103. In response to stress, GC-MS metabolite profiling showed enhance metabolism in both cultivars’ leaves, as well as in the roots irrespective of the developmental stage of the plant. This evidence combined indicates enhance gas exchange and carbon assimilation when bell pepper is grafted on S103 under low root-zone temperature.
On the future of transportation in an era of automated and autonomous vehicles
Authors: Hancock P. A. , Nourbakhsh Illah , Stewart Jack
Published: January 2019

Automated vehicles (AVs) already navigate US highways and those of many other nations around the world. Current questions about AVs do not now revolve around whether such technologies should or should not be implemented; they are already with us. Rather, such questions are more and more focused on how such technologies will impact evolving transportation systems, our social world, and the individuals who live within it and whether such systems ought to be fully automated or remain under some form of direct human control. More importantly, how will mobility itself change as these independent operational vehicles first share and then dominate our roadways? How will the public be kept apprised of their evolving capacities, and what will be the impact of science and the communication of scientific advances across the varying forms of social media on these developments? We look here to address these issues and to provide some suggestions for the problems that are currently emerging.
Science audiences, misinformation, and fake news
Authors: Scheufele Dietram A. , Krause Nicole M.
Published: January 2019

Concerns about public misinformation in the United States—ranging from politics to science—are growing. Here, we provide an overview of how and why citizens become (and sometimes remain) misinformed about science. Our discussion focuses specifically on misinformation among individual citizens. However, it is impossible to understand individual information processing and acceptance without taking into account social networks, information ecologies, and other macro-level variables that provide important social context. Specifically, we show how being misinformed is a function of a person’s ability and motivation to spot falsehoods, but also of other group-level and societal factors that increase the chances of citizens to be exposed to correct(ive) information. We conclude by discussing a number of research areas—some of which echo themes of the 2017 National Academies of Sciences, Engineering, and Medicine’sCommunicating Science Effectivelyreport—that will be particularly important for our future understanding of misinformation, specifically a systems approach to the problem of misinformation, the need for more systematic analyses of science communication in new media environments, and a (re)focusing on traditionally underserved audiences.
Limits of long-term selection against Neandertal introgression
Authors: Petr Martin , Pääbo Svante , Kelso Janet , Vernot Benjamin
Published: January 2019

Significance

Since the discovery that all non-Africans inherit 2% of their genomes from Neandertal ancestors, there has been a great interest in understanding the fate and effects of introgressed Neandertal DNA in modern humans. A number of recent studies have claimed that there has been continuous selection against introgressed Neandertal DNA over the last 55,000 years. Here, we show that there has been no long-term genome-wide removal of Neandertal DNA, and that the previous result was due to incorrect assumptions about gene flow between African and non-African populations. Nevertheless, selection did occur following introgression, and its effect was strongest in regulatory regions, suggesting that Neandertals may have differed from humans more in their regulatory than in their protein-coding sequences.
Varroa destructorfeeds primarily on honey bee fat body tissue and not hemolymph
Authors: Ramsey Samuel D. , Ochoa Ronald , Bauchan Gary , Gulbronson Connor , Mowery Joseph D. , Cohen Allen , Lim David , Joklik Judith , Cicero Joseph M. , Ellis James D. , Hawthorne David , vanEngelsdorp Dennis
Published: January 2019

Significance

Varroa destructorcauses considerable damage to honey bees and subsequently the field of apiculture through just one process: feeding. For five decades, we have believed that these mites consume hemolymph like a tick consumes blood, and thatVarroacause harm primarily by vectoring viruses. Our work shows that they cause damage more directly.Varroaexternally digest and consume fat body tissue rather than blood. These findings explain the failure of some previous attempts at developing effectively targeted treatment strategies forVarroacontrol. Furthermore, it provides some explanation for the diverse array of debilitating pathologies associated withVarroathat were unexplained by hemolymph removal alone. Our work provides a path forward for the development of novel treatment strategies forVarroa.
Molecular and Cellular Effect of Angiotensin 1–7 on Hypertensive Kidney Disease
Authors: Chen Yuanjian , Zhao Wenyuan , Liu Chang , Meng Weixin , Zhao Tieqiang , Bhattacharya Syamal K , Sun Yao
Published: January 2019

BACKGROUND

Studies implicate that angiotensin 1–7 (Ang1-7) imparts protective effects in the kidney. However, its relevance in hypertensive kidney disease is not fully understood. The purpose of this study was to explore the role of Ang1-7 on renal damage/remodeling during hypertension and its potential underlying molecular–cellular mechanisms.

METHODS

Hypertension was induced in adult Sprague–Dawley rats by infusion of aldosterone (ALDO; 0.75 μg/hour) for 4 weeks with or without co-treatment of Ang1-7 (1 mg/kg/day). Untreated rats served as controls. Systolic blood pressure was monitored by tail-cuff technique. Renal fibrosis was evaluated by picrosirius red staining and renal collagen volume fraction was quantitated using imaging analyzing system. The expression of profibrotic factors [transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-D (PDGF-D), fibroblast growth factor-1 (FGF-1), vascular endothelial growth factor-D (VEGF-D), and tissue inhibitors of metalloproteinases (TIMPs)] and free radical producing enzymes (inducible nitric oxide synthase and nicotinamide adenine dinucleotide phosphate [NADPH] oxidase) in the kidney were examined by reverse transcription–polymerase chain reaction and western blot. Renal oxidative stress was assessed by malondialdehyde (MDA) measurement.

RESULTS

Chronic ALDO infusion caused hypertension and hypertensive renal disease represented as glomerular damage/sclerosis. Ang1-7 co-treatment did not affect blood pressure in ALDO-treated rats, but significantly attenuated the glomerular damage/fibrosis. ALDO treatment significantly elevated renal expression of profibrogenic factors, including TGF-β1, TIMP-1/TIMP-2, FGF-1, PDGF-D, and VEGF-D, whereas Ang1-7 co-treatment significantly reduced renal TGF-β1, TIMP-1/TIMP-2, and FGF-1, but not PDGF-D and VEGF-D. Furthermore, ALDO infusion elevated NADPH oxidase (gp91phox) and MDA in the kidney, which was attenuated by Ang1-7 co-treatment.

CONCLUSIONS

Ang1-7 plays a protective role in the hypertensive kidney disease independent of blood pressure. The beneficial effects of Ang1-7 are likely mediated via suppressing TGF-β/FGF-1 pathways and oxidative stress.
SRG extractor: a skinny reference genome approach for reduced-representation sequencing
Authors: Torkamaneh Davoud , Laroche Jérôme , Rajcan Istvan , Belzile François
Published: January 2019

Motivation

Reduced-representation sequencing is a genome-wide scanning method for simultaneous discovery and genotyping of thousands to millions of single nucleotide polymorphisms that is used across a wide range of species. However, in this method a reproducible but very small fraction of the genome is captured for sequencing, while the resulting reads are typically aligned against the entire reference genome.

Results

Here we present a skinny reference genome approach in which a simplified reference genome is used to decrease computing time for data processing and to increase single nucleotide polymorphism counts and accuracy. A skinny reference genome can be integrated into any reduced-representation sequencing analytical pipeline.

Availability and implementation

https://bitbucket.org/jerlar73/SRG-Extractor.

Supplementary information

Supplementary data are available at Bioinformatics online.
Generalized rich-club ordering in networks
Authors: Cinelli Matteo
Published: January 2019

Rich-club ordering refers to the tendency of nodes with a high degree to be more interconnected than expected. In this article, we consider the concept of rich-club ordering when generalized to structural measures that differ from the node degree and to non-structural measures (i.e. to node metadata). The differences in considering rich-club ordering with respect to both structural and non-structural measures is then discussed in terms of employed coefficients and of appropriate null models (link rewiring vs. metadata reshuffling). Once a framework for the evaluation of generalized rich-club ordering is defined, we investigate such a phenomenon in real networks provided with node metadata. By considering different notions of node richness, we compare structural and non-structural rich-club ordering, observing how external information about the network nodes is able to validate the presence of rich-clubs in networked systems.
Homografts versus stentless bioprosthetic valves in the pulmonary position: a multicentre propensity-matched comparison in patients younger than 20 years†
Authors: Marathe Supreet P , Bell Douglas , Betts Kim , Sayed Sajid , Dunne Benjamin , Ward Cameron , Whight Chris , Jalali Homayoun , Venugopal Prem , Andrews David , Alphonso Nelson
Published: January 2019

OBJECTIVES

The aim of this study was to compare the performance of pulmonary homografts with stentless bioprosthetic valves [Medtronic Freestyle™ (Medtronic, Minneapolis, MN, USA)] in the pulmonary position in patients with congenital heart disease (CHD) younger than 20 years.

METHODS

Between January 2000 and December 2017, 215 patients were retrospectively identified from hospital databases in 3 congenital heart centres in Australia. Valve performance was evaluated using standard criteria. Propensity score matching was used to balance the 2 treatment groups.

RESULTS

Freedom from reintervention for patients who received a pulmonary homograft (n = 163) was 96%, 88% and 81% at 5, 10 and 15 years and for patients who received a Freestyle™ valve (n = 52) was 98%, 89% and 31% at 5, 10 and 15 years, respectively. Freedom from structural valve degeneration for patients with a homograft was 92%, 87% and 77% at 5, 10 and 15 years and for patients with a Freestyle valve was 96%, 80% and 14% at 5, 10 and 15 years, respectively. In the first 10 years, there was no difference in outcomes [reintervention hazard ratios (HR) = 0.69, 95% confidence intervals (CI) (0.20–2.42), P = 0.56; structural valve degeneration HR = 0.92 (0.34–2.51), P = 0.87]. After 10 years, the recipients of the Freestyle valves were at higher risk of both outcomes [reintervention HR = 7.89; 95% CI (2.79–22.34), P < 0.001; structural valve degeneration HR = 7.41 (2.77–19.84), P < 0.001]. The findings were similar when analysed by implantation in the orthotopic position and in the propensity-matched groups.

CONCLUSIONS

The Freestyle stentless bioprosthetic valve is a comparable alternative to cryopreserved pulmonary homografts up to 10 years after implantation when implanted in an orthotopic pulmonary position in patients younger than 20 years with CHD.
Decomposition Rules for the Ring of Representations of Non-Archimedean GLn
Authors: Gurevich Maxim
Published: January 2019

Let $\mathcal{R}$ be the Grothendieck ring of complex smooth finite-length representations of the sequence of p-adic groups $\{GL_n(F)\}_{n=0}^\infty $, with multiplication defined through parabolic induction. We study the problem of the decomposition of products of irreducible representations in $\mathcal{R}$. We obtain a necessary condition on irreducible factors of a given product by introducing a width invariant. Width $1$ representations form the previously studied class of ladder representations. We later focus on the case of a product of two ladder representations, for which we establish that all irreducible factors appear with multiplicity one. Finally, we propose a general rule for the composition series of a product of two ladder representations and prove its validity for cases in which the irreducible factors correspond to smooth Schubert varieties.
Prostanoids and leukotrienes in the pathophysiology of atopic dermatitis and psoriasis
Authors: Honda Tetsuya , Kabashima Kenji
Published: January 2019

Lipid mediators, such as prostanoids and leukotrienes (LTs), exert a range of actions through their own receptors on cell surfaces in various pathophysiological conditions. It has been reported that the production of prostanoids and LTs is significantly elevated in the skin lesions of some chronic inflammatory skin diseases, such as atopic dermatitis (AD) and psoriasis, showing the possible involvement of these lipid mediators in the development of those diseases. Although the actual significance of these lipid mediators in humans is still unclear, the findings from studies in mice suggest diverse roles of the lipid mediators in the progression or regulation of these diseases. For example, in a mouse AD model, prostaglandin D2 inhibits the induction of Th2 cells through DP receptor on Langerhans cells, while it promotes infiltration of Th2 cells through chemoattractant receptor-homologous molecule expressed on Th2 cells. In a psoriasis model, thromboxane A2-TP signaling promotes psoriatic dermatitis by facilitating IL-17 production from γδ T cells. In this short review, we summarize the current findings on the roles of prostanoids and LTs in AD and psoriasis as revealed by studies in mice, and discuss the potential of these lipid mediators as therapeutic targets in humans.
Antigen presentation and adaptive immune responses in skin
Authors: Honda Tetsuya , Egawa Gyohei , Kabashima Kenji
Published: January 2019

For the induction of adequate cutaneous immune responses, the antigen presentation and recognition that occur in both the skin and skin-draining lymph nodes are essential. In each process of cutaneous immune responses, several distinct subsets of immune cells, including dendritic cells and T cells, are involved, and they elicit their respective functions in a harmonious manner. For example, in the elicitation phase of cutaneous acquired immunity, immune cells form a specific lymphoid structure named inducible skin-associated lymphoid tissue (iSALT) to facilitate efficient antigen presentation in situ. In this short review, we will overview the mechanisms of how antigens are presented and how cutaneous adaptive immune responses are conducted in the skin, especially focusing on contact hypersensitivity, a prototypic adaptive immune response in the skin.
Prevalence of Aggression in Displaced Syrian Adolescents Attending Afternoon Public Schools in Beirut
Authors: Bouclaous Carmel , El Safadi Ali , Basbous Mazen , Haddad Iskander , Mahdi Ahmad , Zibara Victor , Ghazi Rabih , Naamani Karim , El Karaaoui Jalal , Salameh Rim
Published: January 2019

We assessed aggression in displaced Syrian adolescents, aged 11 years and above, enrolled in Beirut's public schools during 2017–2018. Of 729 parental consent forms distributed in nine randomly selected schools, 368 (50.5%) parents accepted to involve their children. Eventually, the revised Buss-Perry aggression questionnaire was used to assess physical aggression, verbal aggression, anger, and hostility in 178 boys and 182 girls. Scores were interpreted based on the adolescents' age, sex, year of arrival to Lebanon, and Syrian governorate from which they migrated last. Twenty four percent of participants scored high on aggression measurements. Boys had significantly higher scores than girls on verbal aggression (p=0.001), hostility (p=0.003) and total aggression (p=0.007). When other variables were held constant, adolescents who fled to Lebanon in the early days of the Syrian war had significantly higher levels of verbal aggression (p=0.044), hostility (p=0.028) and total aggression (p=0.007) than those who arrived later. Anger scores were not particularly affected by variables in our regression model. Adolescents from Idlib, Daraa, and Aleppo were predicted to have increased physical aggression scores. Verbal aggression scores were predicted to rise for adolescents from Daraa and Aleppo while other districts had a protective effect. These adolescents have witnessed the harshness and inhumanity of war, and have survived life-changing traumatic events. In view of our results, we recommend the introduction of a school-based universal cognitive behavioral intervention to reduce aggression in this vulnerable group both in Lebanon and upon their return to Syria.
The politics of migrant dispersal. Dividing and policing migrant multiplicities
Authors: Tazzioli Martina
Published: January 2019

This article focuses on the politics of migrant dispersal that has been enforced in Europe for regaining control over ‘unruly’ migrants’ presence and movements, with a specific focus on the French and on the Italian contexts. The article shows that dispersal can be considered as a spatial strategy of governmentality and that far from being a new policy, it was already adopted to manage former colonised populations. The article argues that strategies of migrant dispersal are today enacted by state authorities, in collaboration with humanitarian actors, for troubling migrants’ presence and autonomous movements, as well as for disrupting and dividing temporary migrant collective formations. First, it retraces a colonial genealogy of dispersal, as a political technology used for disciplining unruly populations. Then, it analyses how dispersal strategies have been put into place in France (Calais and Paris) and in Italy (Ventimiglia) not only by scattering migrants across space but also by dismantling migrant spaces of life (‘lieux de vie’). The article moves on demonstrating that the politics of dispersal is mainly enforced for preventing the consolidation of migrant multiplicities, criminalising them as ‘migrant mobs’ and spatially dividing them. The third section of the article brings attention to the effects of migrants’ forced hypermobility and to the convoluted geographies that dispersal triggers. It concludes by bringing attention to the increasing criminalisation of migrant support networks that try to prevent the dismantling of migrant autonomous spaces.