bluuebunny/crossref_metadata_2025 huggingface dataset:
Bots fired: examining social bot evidence in online mass shooting conversations
Authors: Schuchard Ross , Crooks Andrew , Stefanidis Anthony , Croitoru Arie
Published: December 2019

Mass shootings, like other extreme events, have long garnered public curiosity and, in turn, significant media coverage. The media framing, or topic focus, of mass shooting events typically evolves over time from details of the actual shooting to discussions of potential policy changes (e.g., gun control, mental health). Such media coverage has been historically provided through traditional media sources such as print, television, and radio, but the advent of online social networks (OSNs) has introduced a new platform for accessing, producing, and distributing information about such extreme events. The ease and convenience of OSN usage for information within society’s larger growing reliance upon digital technologies introduces potential unforeseen risks. Social bots, or automated software agents, are one such risk, as they can serve to amplify or distort potential narratives associated with extreme events such as mass shootings. In this paper, we seek to determine the prevalence and relative importance of social bots participating in OSN conversations following mass shooting events using an ensemble of quantitative techniques. Specifically, we examine a corpus of more than 46 million tweets produced by 11.7 million unique Twitter accounts within OSN conversations discussing four major mass shooting events: the 2017 Las Vegas concert shooting, the 2017 Sutherland Springs church chooting, the 2018 Parkland School Shooting and the 2018 Santa Fe school shooting. This study’s results show that social bots participate in and contribute to online mass shooting conversations in a manner that is distinguishable from human contributions. Furthermore, while social bots accounted for fewer than 1% of total corpus user contributors, social network analysis centrality measures identified many bots with significant prominence in the conversation networks, densely occupying many of the highest eigenvector and out-degree centrality measure rankings, to include 82% of the top-100 eigenvector values of the Las Vegas retweet network.
Inorganic halide perovskite materials and solar cells
Authors: Zhang Cuiling , Arumugam Gowri Manohari , Liu Chong , Hu Jinlong , Yang Yuzhao , Schropp Ruud E. I. , Mai Yaohua
Published: December 2019

Organic-inorganic perovskite solar cells (PSCs) have achieved an inspiring third-party-certificated power conversion efficiency (PCE) of 25.2%, which is comparable with commercialized silicon (Si) and copper indium gallium selenium solar cells. However, their notorious instability, including their deterioration at elevated temperature, is still a serious issue in commercial applications. This thermal instability can be ascribed to the high volatility and reactivity of organic compounds. As a result, solar cells based on inorganic perovskite materials have drawn tremendous attention, owing to their excellent stability against thermal stress. In the last few years, PSCs based on inorganic perovskite materials have seen an astonishing development. In particular, CsPbI3 and CsPbI2Br PSCs demonstrated outstanding PCEs, exceeding 18% and 16%, respectively. In this review, we systematically discuss the properties of inorganic perovskite materials and the device configuration of inorganic PSCs as well as review the progress in PCE and stability. Encouragingly, all-inorganic PSCs, in which all functional layers are inorganic, provide a feasible approach to overcome the thermal instability issue of traditional organic-inorganic PSCs, leading to new perspectives toward commercial production of PSCs.
Chaos detection of Duffing system with fractional-order derivative by Melnikov method
Authors: Niu Jiangchuan , Liu Ruyu , Shen Yongjun , Yang Shaopu
Published: December 2019

The chaos detection of the Duffing system with the fractional-order derivative subjected to external harmonic excitation is investigated by the Melnikov method. In order to apply the Melnikov method to detect the chaos of the Duffing system with the fractional-order derivative, it is transformed into the first-order approximate equivalent integer-order system via the harmonic balance method, which has the same steady-state amplitude-frequency response equation with the original system. Also, the amplitude-frequency response of the Duffing system with the fractional-order derivative and its first-order approximate equivalent integer-order system are compared by the numerical solutions, and they are in good agreement. Then, the analytical chaos criterion of the Duffing system with the fractional-order derivative is obtained by the Melnikov function. The bifurcation and chaos of the Duffing system with the fractional-order derivative and an integer-order derivative are analyzed in detail, and the chaos criterion obtained by the Melnikov function is verified by using bifurcation analysis and phase portraits. The analysis results show that the Melnikov method is effective to detect the chaos in the Duffing system with the fractional-order derivative by transforming it into an equivalent integer-order system.
A compact device for simultaneous dielectric spectroscopy and microgravimetric analysis under controlled humidity
Authors: Gennaro Alessia , Rosa Antonio S. , Cornelis Peter , Pfeiffer Helge , Disalvo Edgardo A. , Wagner Patrick , Wübbenhorst Michael
Published: December 2019

Water plays a key role in the functioning of natural and synthetic molecular systems. Despite several hydration studies, different techniques are employed individually for monitoring different physical features such as kinetics, dynamics, and absorption. This study describes a compact hydration cell that enables simultaneous dielectric relaxation spectroscopy (DRS) and mass loss/uptake measurements in thin organic layers under controlled humidity conditions and in a wide temperature range. This approach enabled us to correlate the physical quantities obtained during the same experiment by complementary techniques. To demonstrate the performance of this device, a 200 nm thick poly(methyl methacrylate) (PMMA) layer was measured at various relative humidity levels (0%–75%), temperatures (25–75 °C), and frequencies (DRS: 0.1 Hz–1 MHz) to study how hydration and dehydration processes affect its molecular dynamics. The results show the capability of this setup to study the changes in the PMMA film regarding the kinetics and molecular dynamics upon variation of the water content.
Effect of nanochannel geometry on electrokinetic ion transport in a micro-nanofluidic system
Authors: Wang Jun-yao , Hou Qi
Published: December 2019

In this paper, the electrokinetic ion transportation in a micro-nanofluidic system is demonstrated through employing Poisson-Nernst-Planck equations coupled with Navier-Stokes equations. The effects of nanochannel geometry, volumic surface charge density, nanochannel length and nanochannel radius on the electric field, ion transport field, and fluid field are investigated. Theoretical research shows that the potential drop relies mainly on the nanochannel’s volume instead of nanochannel geometry. Two acute-angle structures in a trapezoid nanochannel relative to a right-angle structure in a semicircular or rectangular nanochannel can intensify the electric double layer field. For a cross sectional shape of the trapezoid, a higher ion concentration is obtained through enhancing the volumic surface electric charge, increasing the nanochannel length, and decreasing the radius. The results enabled the provision of a beneficial method for better understanding the design principle of the nanochannel structure.
Dissipative character of asymptotics for the nonlinear fractional Schrödinger equation
Authors: Naumkin Pavel I.
Published: December 2019

We consider the Cauchy problem for the fractional nonlinear Schrödinger equation i∂tu+25∂x52u=λu52u, where λ∈R. We obtain the large time asymptotic behavior of solutions, which has a self-similar behavior and a logarithmic modification compared with the corresponding linear problem.
Pyrolysis and combustion characteristics and reaction kinetics of carbon fiber/epoxy composites
Authors: Wang Haiyan , Zhang Lei
Published: December 2019

The pyrolysis and combustion characteristics and reaction kinetics of epoxy resin matrix and carbon fiber/epoxy composites based on epoxy resin were studied by cone calorimetry and thermogravimetry. The results show that with the increase in thermal radiation intensity (increase from 25 kW m−2 to 55 kW m−2), the average ignition time of the experimental samples decreases, the peak heat release rate increases, and the peak appears earlier. Carbon fiber can inhibit the pyrolysis and combustion of epoxy resin. It can effectively inhibit the droplet and splash phenomenon during the combustion process. The time of ignition, heat release, and the peak value of the heat release rate are delayed. The ignition temperature of foam core materials in carbon fiber/epoxy foam laminates is low, which makes the average ignition time and peak heat release rate appear earlier. The theoretical critical heat fluxes of four experimental samples (epoxy resin matrix, carbon fiber/epoxy bidirectional woven fabric, carbon fiber/epoxy prepreg, and carbon fiber/epoxy foam laminate) were obtained by calculation. The theoretical critical heat fluxes are 12.12 kW m−2, 13.21 kW m−2, 11.12 kW m−2, and 0.93 kW m−2, respectively. The pyrolysis of carbon fiber/epoxy bidirectional woven fabric can be divided into three stages: two stages of epoxy resin matrix decomposition and carbon fiber decomposition. The heating rate has a significant influence on the pyrolysis process. With the increase in heating rate, the maximum weight loss rate temperature moves toward high temperature. The Kissinger method and Flynn-Wall-Ozawa method were used to analyze the pyrolysis kinetics. The apparent activation energy and pre-exponential factors were obtained at different heating rates. The results obtained by the two methods are basically the same. When the pyrolysis temperature of the three composites reached 450 °C, the mass loss was 20%, 17%, and 28%, respectively. This shows that the thermal stability of carbon fiber/epoxy prepreg is the best, the thermal stability of the two-way woven fabric of carbon fiber is better, and the thermal stability of the carbon fiber sandwich board is the weakest. It is consistent with this rule at any temperature.
First-principles study of Pd-MoSe2 as sensing material for characteristic SF6 decomposition components
Authors: Qian Hai , Deng Jun , Zhou Haibin , Yang Xu , Chen Wei
Published: December 2019

SF6 decomposition component detection is an effective way to diagnose the severity and type of electric discharge. In this study, MoSe2 based material has been chosen as the gas sensing material for the detection of SOF2 and SO2F2, the two characteristic decomposition components of SF6. Based on density functional theory calculations, the adsorption properties of both SOF2 and SO2F2 on intrinsic and Pd doped MoSe2 are studied by analyzing the adsorption structure, charge transfer, density of states, and molecular orbit. The results show that SOF2 and SO2F2 adsorb on intrinsic MoSe2 by physisorption, resulting in weak gas sensitivity. After Pd doping on MoSe2, it dramatically enhances the gas sensitivity of MoSe2 to SOF2 and SO2F2; both the gases interact with Pd-MoSe2 by chemisorption. In addition, SOF2 and SO2F2 show an increase in conductivity during the adsorption process to different extents. The calculation results show that Pd-MoSe2 can be a potential gas sensing material for SOF2 and SO2F2 detection in SF6-insulated equipment.
Biodegradable transient resistive random-access memory based on MoO3/MgO/MoO3 stack
Authors: Fang Sheng Li , Liu Wei Hua , Li Xin , Wang Xiao Li , Geng Li , Wu Min Shun , Huang Xiao Dong , Han Chuan Yu
Published: December 2019

High-performance biodegradable transient resistive random-access memories (RRAMs) with the structure of Mg/MoO3/MgO/MoO3/Mg have been fabricated on a polylactic acid (PLA) substrate. Without the electroforming process, the devices have high ratios of the high-resistance state (HRS)/low-resistance state (LRS) (>50% of devices reaching above 106 and ∼3% reaching above 1011), good retention properties (both the HRS and LRS without deterioration within 2 × 104 s), and good endurance properties (continuously switched between the HRS and LRS >100 times under appropriate voltage pulses). By investigating the effect of different top electrode (TE) and bottom electrode (BE) combinations (TE/BE: Mg/Mg, Pt/Mg, Mg/Pt, and Mg/Au) and different oxygen contents of MoO3 on the performance of devices, the resistive switching mechanism is revealed to be the redox of the Mg TE at the interface of Mg/MoO3. The HRS is attributed to the formation of MgO after Mg is oxidized by mobile oxygen ions or oxygen captured from adjacent MoO3 under applied voltage, while the LRS is ascribed to the dissolution of formed MgO. The fitting results of the measured data indicate that the conduction of the HRS is dominated by the Poole-Frenkel (P-F) emission and that of the LRS is governed by the Ohmic conduction. Moreover, the devices can degrade quickly in 0.9% NaCl solution within 5 h, except for the PLA substrate that is able to degrade in the human body.
Exploiting locality and translational invariance to design effective deep reinforcement learning control of the 1-dimensional unstable falling liquid film
Authors: Belus Vincent , Rabault Jean , Viquerat Jonathan , Che Zhizhao , Hachem Elie , Reglade Ulysse
Published: December 2019

Instabilities arise in a number of flow configurations. One such manifestation is the development of interfacial waves in multiphase flows, such as those observed in the falling liquid film problem. Controlling the development of such instabilities is a problem of both academic interest and industrial interest. However, this has proven challenging in most cases due to the strong nonlinearity and high dimensionality of the underlying equations. In the present work, we successfully apply Deep Reinforcement Learning (DRL) for the control of the one-dimensional depth-integrated falling liquid film. In addition, we introduce for the first time translational invariance in the architecture of the DRL agent, and we exploit locality of the control problem to define a dense reward function. This allows us to both speed up learning considerably and easily control an arbitrary large number of jets and overcome the curse of dimensionality on the control output size that would take place using a naïve approach. This illustrates the importance of the architecture of the agent for successful DRL control, and we believe this will be an important element in the effective application of DRL to large two-dimensional or three-dimensional systems featuring translational, axisymmetric, or other invariance.
Probing the dopant profile in nanoscale devices by low temperature electrostatic force microscopy
Authors: Wang Wanqing , Fan Zhao , Chen Kaixiang , Wei Hao , Dan Yaping
Published: December 2019

Probing dopant distributions in nanoscale devices may find important applications in failure analysis. In this work, we employed cryogenic electrostatic force microscopy (EFM) to probe the dopant distribution in a lateral nanoscale bipolar junction transistor formed by ion implantations. The photocurrent characteristics under light illumination show that the devices were made properly. The distributions of phosphorus and boron dopants are visible in the phase domain of EFM when the operating temperature is lowered to 130 K from room temperature. Numerical simulations show that the phase shifts for the doping regions are largely consistent with the experimental data.
Correlating ecotoxicological early-warning systems to biotic indices to assess riverine teratogenic contamination
Authors: Cera Alessandra , Ceschin Simona , Del Grosso Floriano , Traversetti Lorenzo , Scalici Massimiliano
Published: December 2019

We constructed a new ecotoxicological tool to test for the presence of teratogens in rivers by exploiting the regenerative capabilities of Hydra vulgaris because using living organisms is considered good practice in environmental monitoring for detecting detrimental pressures. Outputs on the Hydra assay were integrated with two biotic indices based on benthic invertebrates and macrophytes to evaluate whether the assay acts as a tool for detecting generalised freshwater conditions or as a biological test model revealing only the effects of dissolved teratogens. Several hypostomae of H. vulgaris were reared in waters collected in diverse southern central Latium rivers, where physiochemical descriptors were surveyed for environmental characterisation. The regeneration rate and amount of aberrations were evaluated to obtain a teratogenic risk index (TRI) score and then compared with the control. TRI calculations showed 4 sites (18.18%) in Class I (no risk), 15 sites (68.18%) in Class II (low risk), 2 sites (9.09%) in Class III (moderate risk) and 1 site (4.55%) in Class IV (high risk). No Class V sites (very high risk) were found. No significant correlations emerged among physicochemical parameters (except for PO43–), environmental descriptors, Simpson diversity indices and biotic indices and the TRI. These results promote an integrated approach to improving links between biological and ecological responses to anthropogenic impacts.
Gene- and tissue-level interactions in normal gastrointestinal development and Hirschsprung disease
Authors: Chatterjee Sumantra , Nandakumar Priyanka , Auer Dallas R. , Gabriel Stacey B. , Chakravarti Aravinda
Published: December 2019

The development of the gut from endodermal tissue to an organ with multiple distinct structures and functions occurs over a prolonged time during embryonic days E10.5–E14.5 in the mouse. During this process, one major event is innervation of the gut by enteric neural crest cells (ENCCs) to establish the enteric nervous system (ENS). To understand the molecular processes underpinning gut and ENS development, we generated RNA-sequencing profiles from wild-type mouse guts at E10.5, E12.5, and E14.5 from both sexes. We also generated these profiles from homozygous
Ret
null embryos, a model for Hirschsprung disease (HSCR), in which the ENS is absent. These data reveal 4 major features: 1) between E10.5 and E14.5 the developmental genetic programs change from expression of major transcription factors and its modifiers to genes controlling tissue (epithelium, muscle, endothelium) specialization; 2) the major effect of
Ret
is not only on ENCC differentiation to enteric neurons but also on the enteric mesenchyme and epithelium; 3) a muscle genetic program exerts significant effects on ENS development; and 4) sex differences in gut development profiles are minor. The genetic programs identified, and their changes across development, suggest that both cell autonomous and nonautonomous factors, and interactions between the different developing gut tissues, are important for normal ENS development and its disorders.
T cell receptor specificity drives accumulation of a reparative population of regulatory T cells within acutely injured skeletal muscle
Authors: Cho Jun , Kuswanto Wilson , Benoist Christophe , Mathis Diane
Published: December 2019

Foxp3
+
CD4
+
regulatory T cells (Tregs) play important roles in controlling both homeostatic processes and immune responses at the tissue and organismal levels. For example, Tregs promote muscle regeneration in acute or chronic injury models by direct effects on local muscle progenitor cells, as well as on infiltrating inflammatory cells. Muscle Tregs have a transcriptome, a T cell receptor (TCR) repertoire, and effector capabilities distinct from those of classical, lymphoid-organ Tregs, but it has proven difficult to study the provenance and functions of these unique features due to the rarity of muscle Tregs and their fragility on isolation. Here, we attempted to sidestep these hindrances by generating, characterizing, and employing a line of mice carrying rearranged transgenes encoding the TCRα and TCRβ chains from a Treg clone rapidly and specifically expanded within acutely injured hindlimb muscle of young mice. Tregs displaying the transgene-encoded TCR preferentially accumulated in injured hindlimb muscle in a TCR-dependent manner both in the straight transgenic model and in adoptive-transfer systems; non-Treg CD4
+
T cells expressing the same TCR did not specifically localize in injured muscle. The definitive muscle-Treg transcriptome was not established until the transgenic Tregs inhabited muscle. When crossed onto the
mdx
model of Duchenne muscular dystrophy, the muscle-Treg TCR transgenes drove enhanced accumulation of Tregs in hindlimb muscles and improved muscle regeneration. These findings invoke the possibility of harnessing muscle Tregs or their TCRs for treatment of skeletal muscle pathologies.
Detailed characterisation of the LEIR intensity limitations for a Pb ion beam
Authors: Saa Hernandez A , Bartosik H , Biancacci N , Hirlander S , Moreno D , Zampetakis M
Published: December 2019

The equilibrium emittance of the Pb beam in the CERN Low Energy Ion Ring (LEIR) results from the interplay of electron cooling and heating processes, as intra-beam scattering and space charge. In this paper we present the measurements of the emittance evolution as a function of intensity, working point and resonance excitation, and compare them with the simulations of the heating processes. Optimum settings for normal and skew sextupoles have been found for the compensation of resonances excited by the lattice.
Space Charge Driven Resonances in the CERN PS
Authors: Asvesta F , Bartosik H , Huschauer A , Papaphilippou Y
Published: December 2019

In the CERN Proton Synchrotron space charge driven resonances are excited around the operational working point due to the periodicity of the optics functions. In this paper, the resonances are studied using analytical methods, i.e. the evaluation of the resonance driving terms connected to the space charge potential of Gaussian distributions. Furthermore, the resonances are characterized in measurements and simulations for various beams. The beams considered are different in terms of brightness, in order to study the dependence of the resonance strength on the space charge force.
Effect of beam-beam kick on electron beam quality in first bunched electron cooler
Authors: Seletskiy S. , Blaskiewicz M. , Fedotov A. , Kayran D. , Kewisch J.
Published: December 2019

The low energy RHIC electron cooler (LEReC) currently under commissioning at BNL is going to be the first non-magnetized bunched electron cooler (EC). For successful cooling LEReC requires that the electrons in the cooling section (CS) have small angles with respect to co-propagating ions. Since there is no strong magnetic field in the CS, the effects of ions on both the trajectory and focusing of the e-bunches is critical. In this paper we consider the ion beam kick on the electron bunches and derive requirements to the respective alignment of electron and ion beams in non-magnetized coolers.
Development of a beam window protection system for the J-PARC linac
Authors: Takahashi H , Hatakeyama S , Sawabe Y , Miyao T , Ishiyama T , Suzuki T
Published: December 2019

In J-PARC Linac, some beam dumps are used for beam conditioning and study. A beam window is installed in the beam line of the beam dump. In 2018, a beam study using a 0- degree beam dump in the Linac resulted in damage to the beam window when the beam intensity has exceeded the tolerance. So as not to repeat this experience, it was decided to immediately advance the development of a beam window protection system. The present paper describes the protection system built as an emergency measure and the tests of its performance.
Time Varying RF Phase Noise for Longitudinal Emittance Blow-up
Authors: Albright S , Quartullo D
Published: December 2019

RF phase noise was shown to be effective for controlled longitudinal emittance blow-up in the Proton Synchrotron Booster (PSB) at CERN during beam tests in 2017, with further developments in 2018. At CERN, RF phase noise is used operationally in the Super Proton Synchrotron (SPS) and Large Hadron Collider (LHC). In this paper we show that it is suitable for operation with a variety of beam types in the PSB. In the PSB the synchrotron frequency changes by approximately a factor 4 during the 500 ms acceleration ramp, requiring large changes in the frequency band of the noise. During 2018, a new method of calculating the noise parameters has been demonstrated, which gives upper and lower bounds to the noise frequency band that are smoothly varying through the ramp. The new calculation method has been applied to operational beams accelerated in both single and double RF harmonics, the final results are presented here.
Evaluation of 2-D Transverse Beam Profile Monitor Using Gas Sheet at J-PARC LINAC
Authors: Kamiya J , Okabe K. , Kinsho M. , Moriya K. , Yamada I. , Ogiwara N. , Hikichi Y. , Wada K.
Published: December 2019

A transverse beam profile monitor, which detects ions or luminescence generated by the interaction between the beam and the gas molecules distributed in a sheet shape, has been developed in the J-PARC LINAC. To know about the gas density distribution of the sheet-shaped gas, which affects the intensity distribution of the detected signal, the calculation by the Monte Carlo simulation code was performed. The calculation results showed that the gas with a narrow width along beam direction distributes enough uniformly within a realistic beam cross-sectional size. In addition, the unsaturated region against the MCP voltage and the injected gas pressure are evaluated based on the measurement with a beam. The results showed that the measurement in the low injected gas pressure with the appropriate applied voltage range is important to measure the beam profile in the unsaturated region.
Lasers for Novel Accelerators
Authors: Gizzi L.A. , Koester P. , Labate L. , Mathieu F. , Mazzotta Z. , Toci G. , Vannini M.
Published: December 2019

Novel accelerator schemes are rapidly emerging in the wake of laser-plasma acceleration research and involve advanced high-power laser drivers for their operation. Significant progress has been made in laser performance during the past decade, including repetition rate, average and peak power, and footprint, making these systems attractive for many applications, including novel accelerators. Here we discuss laser driver requirements for the proposed novel accelerator schemes, examine emerging technologies and introduce a viable laser driver concept for a first generation of plasma accelerators.
Design and construction of 3D Helmholtz coil system to calibrate 3D Hall probes
Authors: Fontanet A. , Marcos J. , Ribó Ll. , Massana V. , Campmany J.
Published: December 2019

In this paper we present the design of a system of 3D Helmholtz coils aimed to generate a magnetic field in any direction in a controlled way. The system is intended to be applied to the detailed characterisation of the response of 3D Hall probes as a function of the orientation of the measured field. The system will generate magnetic fields of up to 5 mT with an expected angular precision of 0.2 mrad.
Dynamic pressure in the LHC: influence of ions induced by ionization of residual gas by both the proton beam and the electron cloud
Authors: Bilgen S. , Bruni C. , Mercier B. , Sattonnay G. , Baglin V.
Published: December 2019

For the future HL-LHC or FCC study, the understanding of the beam interactions with the vacuum chamber is fundamental to provide solutions to mitigate the pressure rises induced by electronic, photonic and ionic molecular desorption. The proton beam circulating in the LHC vacuum chamber ionizes the residual gas producing electrons as well as positive ions. In-situ measurements were carried out, on the LHC Vacuum Pilot Sector during the LHC RUN II, to monitor the dynamic pressure, and to collect the electrical signals due to the electron cloud and to the ions interacting with the vacuum chamber walls. Experimental measurements of electrical signals recorded by copper electrodes were compared to calculations taking into account both the Secondary Electron Yield of copper and electron energy distribution. Finally, it seems that copper electrodes were not fully conditioned and an ion current could be estimated.
Research and design of digital magnet power supply controller for HALS
Authors: Shao Z. X. , Gao H. , Zhang H.Y. , Liu P. , Liu G.W. , Sun X.K.
Published: December 2019

Hefei Advanced Light Source (HALS) is the fourth-generation radiation light source in China which is under design. Ultra-low beam emittance requires higher performance of power supply system. The power supply controller is a key part of the power system. This article describes the design and testing of high-stability power controllers and fast corrector power supply controllers. A new controller architecture is proposed for the problems of the two controllers.
Research progress of power supply system in HALS
Authors: Shao Z. X. , Gao H. , Zhang H.Y. , Liu P. , Liu G.W. , Wang L.
Published: December 2019

Hefei Advanced Light Source (HALS) is the fourth generation light source in China's planning and construction. In order to achieve the diffraction limit of the emission and improve the beam quality, the research on magnet power supply (MPS) technology is essential. We have designed a variety of solutions for different power supplies. We designed the first version of the high stability power supply control card. The first version of the high-stability power supply control card was designed and tested with a small power module. Our pre-research system has developed a corrector magnet power supply with a small signal response bandwidth higher than 10 kHz. The developed prototypes use self-developed controllers, and most of the test results can meet the requirements. This article describes the progress of the HALS power supply system.
Improvement the Bending Magnet Power Supply Performance for TPS Storage RING
Authors: Wang Bao-Sheng , Liu Kuo-Bin , Huang Chih-Hsien , Liu Chen-Yao , Huang Yong-Seng , Huang Jhao-Cyuan
Published: December 2019

In the TPS (Taiwan Photon Source) facility, current stability of the electron beam depends on the bending magnet power supply and an orbit FOFB system to compensate the magnetic field. Due to the output current stability of the bending magnet power supply drifts with temperature so the orbit FOFB system should be applied to fine tune magnetic field and the photon beam should circulate in storage ring. In this paper, to stabilize the temperature of regulation circuit’s temperature box of the bending magnet power supply, the long-term output current stability is improve from ± 50ppm to ± 10ppm, and orbit FOFB system substantially reduce the tune X of beam position, effectively increasing the beam current stability and quality. In the TPS (Taiwan Photon Source) facility, current stability of the electron beam depends on the bending magnet power supply and an orbit FOFB system to compensate the magnetic field. Due to the output current stability of the bending magnet power supply drifts with temperature so the orbit FOFB system should be applied to fine tune magnetic field and the photon beam should circulate in storage ring. In this paper, to stabilize the temperature of regulation circuit’s temperature box of the bending magnet power supply, the long-term output current stability is improve from ± 50ppm to ± 10ppm, and orbit FOFB system substantially reduce the tune X of beam position, effectively increasing the beam current stability and quality.
Further RF measurements on the superconducting 217 MHz CH demonstrator cavity for a CW linac at GSI
Authors: Dziuba F , Aulenbacher K , Barth W , Basten M , Burandt C , Busch M , Conrad T , Gettmann V , Heilmann M , Kürzeder T , Lauber S , List J , Miski-Oglu M , Podlech H , Salvatore J , Schnase A , Schwarz M , Yaramyshev S
Published: December 2019

Recently, the first section of a superconducting (SC) continuous wave (CW) linac has been extensively tested with heavy ion beam from the GSI High Charge State Injector (HLI). During this testing phase, the reliable operability of 217 MHz multi-gap crossbar-H-mode (CH) cavities has been successfully demonstrated. The SC 217 MHz CH cavity (CH-0) of the demonstrator setup accelerated heavy ions up to the design beam energy and even beyond at high beam intensities and full transmission. This worldwide first beam test with a SC CH cavity is a major milestone on the way realizing the entire SC CW linac project. In this contribution further RF measurements on the cavity are presented providing full characterization of the RF structure CH-0.
Low Power RF Test of a Quadrupole-free X-Band Mode Launcher for High Brightness Applications
Authors: Torrisi G. , Sorbello G. , Celona L. , Leonardi O. , Mauro G. , Gammino S. , Castorina G. , Spataro Bruno , Faillace L. , Dolgashev V.
Published: December 2019

In this work we present the low power RF characterization of a novel TM01 X-band mode launcher for the new generation of high brightness RF photo-injectors. The proposed mode launcher exploits a fourfold symmetry which minimizes both the dipole and the quadrupole fields in order to mitigate the emittance growth in the early stages of the acceleration process. Two identical aluminum mode launchers have been assembled and measured in back-to-back configurations for three different central waveguide lengths. From the back-to-back results we infer the performance of each mode launcher. The low power RF test, performed at the Istituto Nazionale di Fisica Nucleare Laboratori Nazionali del Sud (INFN-LNS), validate both the numerical simulations and the quality of fabrication. An oxygen-free high-conductivity copper version of the device is being manufactured for high power and ultra high vacuum tests that are planned to be conducted at SLAC.
Simulations of beam loading compensation in a wideband accelerating cavity using a circuit simulator including a LLRF feedback control
Authors: Tamura Fumihiko , Yamamoto Masanobu , Sugiyama Yasuyuki , Yoshii Masahito , Ohmori Chihiro , Shimada Taihei , Nomura Masahiro , Hasegawa Katsushi , Hara Keigo , Furusawa Masashi
Published: December 2019

Magnetic alloy cavities are employed in the J-PARC RCS to generate high accelerating voltages. The cavity, which is driven by a vacuum tube amplifier, has a wideband frequency response and the beam loading in the cavity is multiharmonic. Therefore, the tube must generate a multiharmonic output current. An LTspice circuit model is developed to analyze the vacuum tube operation and the compensation of the multiharmonic beam loading. The model includes the cavity, tube amplifier, beam current, and LLRF feedback control. The feedback control consists of the I/Q demodulator including low pass filters, PI control, and I/Q modulator. In this article, we present the implementation of the LLRF functions in the LTspice simulations. The preliminary simulation results are also presented. The simulations fairly agree with the beam test results.
Monte Carlo modelling of particle acceleration in collisionless shocks with effective mean electric field
Authors: Osipov S M , Bykov A M , Ellison D C
Published: December 2019

Relativistic particle acceleration in collisionless shocks of supernova remnants is accompanied with magnetic field amplification by cosmic ray (CR) driven plasma instabilities. Bell’s fast CR-current instability is predicted to produce turbulence with a non-zero mean electric field in the shock precursor. We present a Monte Carlo model of Fermi shock acceleration explicitly taking into account an effective mean upstream electric field. Our model is nonlinear and includes the backreaction effects of efficient Fermi acceleration on the shock structure.
Modelling of far ultraviolet emission of pulsar wind nebulae with bow shocks
Authors: Petrov A E , Bykov A M , Osipov S M , Levenfish K P , Uvarov Yu A
Published: December 2019

The kinetic modelling of electron and positron acceleration in the colliding shock flows of pulsar wind nebulae with bow shocks allows to explain the nature of their hard particle spectra. The hard synchrotron emission produced by the accelerated particles can reach the far ultraviolet range (1250 — 2000 Å) providing the maximal luminosity of the bow shock nebulae in this range. In this paper the results of modelling of pulsar wind particles transport in the colliding shock flows in the bow shock nebulae of PSRs J1741-2054 and B1929+10 are presented. The results of the synchrotron emission modelling are confronted to the observations in order to estimate possible far ultraviolet luminosities of the discussed objects.
Differential rotation of the neutron star polar cap
Authors: Vorontsov M V , Barsukov D P
Published: December 2019

The flow in the polar cap region of the neutron star is caused by magnetospheric electric current flow in the pulsar tube due to current closure in the crust and partially in the liquid surface layer. In this paper we consider the flow velocity in case of aligned pulsar with homogeneous vertical magnetic field. Changing of the liquid density and the conductivity with depth is taken into account.
Chemical evolution of cold dark clouds in the vicinity of supernova remnants
Authors: Nesterenok A V
Published: December 2019

The supernova explosion increases cosmic ray and x-ray fluxes in the surrounding interstellar medium. Cosmic ray particles and x-ray radiation penetrate nearby molecular clouds and affect the chemical and thermal evolution of the gas. Here we study chemical changes in the dense molecular gas influenced by a sudden increase of the ionization rate that may be caused by the supernova explosion. At the cloud core density 2 × 104 cm−3, the H atom abundance reaches the equilibrium value at about 3 × 104 yr after the change in irradiation conditions. The response time of abundances of icy mantle species is 104 − 105 yr. The abundances of neutral and grain mantle species may not reach their equilibrium values in molecular clouds in the vicinity of’middle-aged’ supernova remnants.
Interaction of a supernova remnant with a wind of young massive star: MHD simulations
Authors: Badmaev D V , Bykov A M
Published: December 2019

Fast stellar winds of young massive stars and supernovae play an essential role in the evolution of the interstellar medium in the Milky Way. They dominate the dynamics of the active starforming regions in starburst galaxies and in particularly their non-thermal radiation. The non-thermal emission from starburst galaxies NGC 253, M82, NGC 1068 was detected from radio to gamma-rays. To model the observed radiation, one needs to know the complex structure of the flows and magnetic fields in the starforming regions. In this work a 2.5D magnetohydrodynamic (MHD) simulation (i.e., we consider 3D vector fields, but assume a 2D axisymmetric geometry) of the interaction between a stellar wind and a supernova remnant shock wave is carried out using the MHD module of the code PLUTO. The structure of the flows in the collision region is obtained taking into account the magnetic fields of the rotating source stars. We present the profiles of the bulk plasma velocity, density and magnetic field in the collision region. The amplification of regular magnetic fields in such systems is studied.
Konus-UF and Helicon-I gamma-ray burst experiments
Authors: Ulanov M V , Aptekar R L , Golenetskii S V , Frederiks D D , Svinkin D S , Tsvetkova A E
Published: December 2019

We present Konus-UF and Helicon-I, the future space-based experiments designed to study temporal and spectral characteristics of gamma-ray bursts, solar flares, soft gamma-repeater bursts, and other transient phenomena over a wide energy range from 10 keV to 15 MeV. The instruments will be mounted onboard the World Space Observatory–Ultraviolet (WSO-UV) and the InterhelioProbe spacecraft, respectively. The spacecraft orbits are going to be far from the Earth’s magnetosphere, which enables nearly uninterrupted observations of the entire sky under stable background conditions.
Clustering local laws of the dynamics of complex living systems
Authors: Demin S A , Panischev O Yu , Latypov R R
Published: December 2019

In this paper, we generalize the studies of the local laws clustering for dynamics of non-Hamiltonian live systems. We analyze the human heart-rate variability. We use the localization procedure to extract the local properties about the space-time structure of the R–R interval time series. The window-time behavior of the memory functions power spectra reflects the periodic properties in studied dynamics. The age-related alterations in heart-rate variability for young and old testees are manifested in velocity of relaxation. They may be derived by localizing the kinetic and relaxation parameters. These parameters can be considered as the specific predictors of the dynamic intermittency in the initial time signal. The proposed window-time representation of the spectral characteristics, kinetic and relaxation parameters is useful for medical physics and physics of live systems.
FTIR Study of the Secondary Structure of DNA in Complexes with Platinum Coordination Compounds
Authors: Tymchenko E , Glova V , Soldatova A , Chikhirzhina E , Polyanichko A
Published: December 2019

Mechanisms of interaction between antitumor compounds and biological molecules have been being studied for decades. One of the most widely applicable drug is dichlorodiammineplatinum(II) (DDP). In the present work we have analyzed effect of cis- and trans-DDP on secondary structure of DNA, bovine serum albumins and HMGB proteins using FTIR spectroscopy. We have shown that both of the DDP isomers facilitate the formation of albumin dimers. We have also shown that DDP facilitates changes in DNA structure, attributed to DDP binding to DNA bases and DNA cross-linking. Thus, the application of hidden peak analysis of FTIR spectra shown to be informative to structural investigation of DDP complexes with nucleic acids and proteins.
Analysis of the secondary structure of blood serum proteins from patients with multiple myeloma
Authors: Kobeleva M O , Telnaya E A , Plotnikova L V , Garifullin A D , Kuvshinov A Yu , Voloshin S V , Polyanichko A M
Published: December 2019

Infrared spectroscopy of biomolecules is one of the few methods, which combine a relatively simple measurements and a possibility of highly informative structural analysis. The most high-demand field of such investigations is the identification of various pathologies accompanied by changes in the biomolecular structure. In this study the comparative analysis of the secondary structure of blood serum proteins from patients with multiple myeloma and healthy donors was performed using infrared spectroscopy. There is a tendency for reduce the proportion of α-helices in the secondary structure of blood serum proteins in patients with multiple myeloma compared to healthy donors. Thus, infrared spectroscopy reveals difference in the secondary structure of blood serum proteins in patients with multiple myeloma and healthy donors.
Compact static mass spectrometer for medical diagnostics
Authors: Kuleshov D O , Kogan V T , Chichagov Yu V , Bogdanov A A , Antonov A S , Tubol’tsev Yu V , Aruev N N
Published: December 2019

Static mass spectrometer for detecting pathologies in the human organism from to the composition of exhaled air is described in this paper. The instrument is equipped with the capillary and membrane sample intake systems for dynamic investigations of a number of components in the exhaled mixture as well as for determining trace amounts of specific volatile biomarkers accompanying diseases of the respiratory system, blood circulation system, interstitial tract, and endocrine system. Tests of the mass spectrometer with the membrane sample inlet system have shown for one of the markers that the monitoring of acetone vapor in air during the respiratory process can be carried out at a level of ∼1 ppm. Mass spectrometric detection of a number of other markers with a higher (up to two orders of magnitude) penetrability through the membrane as compared to acetone becomes possible at the ppb level. The presented static mass spectrometer was tested for the possibility of working with a linear Ion CCD matrix designed to directly register ions in a wide energy range. The experimental results prove that the selected scheme of the mass spectrometer can be used in combination with both the IonCCD detector and the microchannel plate – IonCCD detector without significantly deteriorating the main performance characteristics of the instrument.
Development of a new technique for quantitative PCR analysis
Authors: Belov D A , Belov Yu V , Kurochkin V E
Published: December 2019

A new technique for automatic determination of the quantification cycle value Cq
is proposed. The technique is based on the third-degree polynomial with a limited range of approximation, which is determined automatically. A reduction in the random error of constructing the calibration dependence in quantitative analyzes of genetically modified soy has been achieved in comparison with the well-known ANK_Shell software of the nucleic acid analyzers ANK.
Influence of lighting spectral characteristics on the lettuce leaf optical properties
Authors: Kuleshova T E , Chernousov I N , Udalova O R , Khomyakov Y V , Aleksandrov A V , Seredin I S , Shcheglov S A , Gall N R , Panova G G
Published: December 2019

The paper concerns the efficiency of light absorption with different spectral composition by lettuce leaves, and the optimal conditions of light environment and mineral nutrition to increase the productivity and quality of plant products grown under artificial lighting. The greatest positive effect has been achieved on the productivity and quality of the lettuce plants Typhoon variety when been grown on the 1N Knop nutrient solution and illuminated with quasi-continuous spectrum in a limited wavelength range in the yellow area with addition of ∼ 10-20% of the total photosynthetically active radiation (PAR) in the near infrared. The most efficient conditions results in the increase on amount of absorbed photon energy by ∼ 40% per gram of plant leaf surface over 10 days when rapid biomass growth and plant development take place. It is proposed to use the index of light absorption, describing the absorption increment with biomass growth, as an indicator for the intensity of light energy processing into biomass.
Microwave Tunable Devices on the YIG-VO2 structures
Authors: Nikitin A A , Vitko V V , Nikitin A A , Ustinov A B , Kalinikos B A
Published: December 2019

The theory describing a tunability of the spin-wave spectrum for the ferrite/vanadium dioxide layered structures through changing the VO2 conductivity is suggested. An influence of the various parameters on the spin-wave wavenumber variations and damping decrement is studied. We show that an effective wavenumber variation with minimal losses is achieved by matching the thicknesses of the ferrite and vanadium dioxide films, as well as the value of external magnetic field. We show also that owing to the electrodynamic interaction, a quality of contact between the ferrite and vanadium dioxide layers is not critical.
Investigation of local ion-stimulated carbon deposition to create vacuum field emission diodes
Authors: Panchenko I V , Shandyba N A , Kolomiytsev A S , Lisitsyn S A
Published: December 2019

This paper presents the results of experimental studies of the influence of the technological parameters of a focused ion beam (FIB) on the process of local ion-stimulated deposition of carbon and tungsten when creating elements of vacuum nanoelectronics. The dependences are obtained illustrating the influence of the time of the FIB exposure at a point on the geometric parameters of the structures. Experimental samples of vacuum field-emission diodes based on semiconductor-metal-dielectric structures were fabricated by ion-stimulated carbon deposition. A technological process for creating field-emission diodes has been developed. The prospects of applying the FIB method for creating structures of vacuum field emission nanoelectronics are demonstrated.