bluuebunny/crossref_metadata_2025 huggingface dataset:
Auslandspatienten: Weniger arabische Medizintouristen
Authors: Kucera Martin
Published: April 2019

Das Geschäft mit Auslandspatienten hat Ärzten und Kliniken im Jahr 2017 Einnahmen von 1,2 Milliarden Euro beschert – ein Rückgang um zwei Prozent gegenüber dem Vorjahr. Hauptgrund ist ein massiver Einbruch medizinischer Behandlungsreisen aus den Golfstaaten. Das Problem ist hausgemacht.
Hauptstadtkongress: „Es geht nicht um die Digitalisierung als Selbstzweck.“
Authors: Dorner Carola
Published: April 2019

Das Motto des Hauptstadtkongresses stellt den digitalen Wandel in den Mittelpunkt. kma sprach mit dem Experten Dr. Daniel Diekmann, der auch als Referent auf dem HSK zu diesem Thema sprechen wird.
Sprechstunde in der PR-Ambulanz: Braucht unsere Klinik einen eigenen Fotografen?
Authors: Endele Kerstin
Published: April 2019

Kerstin Endele ist zur Hälfte Journalistin und zur Hälfte Biochemikerin. Seit mehr als 15 Jahren ist sie Expertin für Gesundheitskommunikation und war fünf Jahre Kommunikationschefin und Pressesprecherin der Charité. Wenn sie nicht Klinikvorstände aus Krisen rettet und Pressesprechern diverser Krankenhäuser dabei hilft, ein bisschen Strategie ins übliche Chaos zu bringen, betreibt sie mit der PR-Ambulanz (www.pr-ambulanz.com) einen der größten Blogs zur Klinikkommunikation in Deutschland.
Ruthenium-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes and Selenocyanates: An Entry to Selenopyridine Derivatives
Authors: Tran Christine , Haddad Mansour , Ratovelomanana-Vidal Virginie
Published: April 2019

A novel synthetic method for the preparation of selenopyridine derivatives, involving a [2+2+2] cycloaddition of α,ω-diynes and selenocyanates that is catalyzed by a ruthenium complex is described. This mild and straightforward reaction allows access to a wide range of selenopyridines with high yields and excellent regioselectivities, using dichloromethane or dichloroethane as solvents, at either 50 or 80 °C. Post-functionalization of halogenated cycloadducts via cyanation using copper and SNAr reaction provides substituted selenopyridines with good yields.
Synthesis of Symmetrical and Hybrid Dimeric Steroids by Double Suzuki–Miyaura Cross Coupling of 4-Bromo-3-oxo Steroids and Benzene-1,4-diboronic Acid
Authors: Mayorquín-Torres Martha C. , Santiago-Sampedro Gerardo I. , Flores-Álamo Marcos , Iglesias-Arteaga Martín. A.
Published: April 2019

Two symmetrical dimers and one hybrid dimer in which the steroid cores are connected by a 1,4-phenylene moiety were obtained by double Suzuki–Miyaura cross coupling of benzene-1,4-diboronic acid with 4-bromo-4-en-3-oxosteroids derived from cholesterol and diosgenin. Detailed NMR characterization of the obtained dimers is described.
Vinyl Sulfoxonium Ylide: A New Vinyl Carbenoid Transfer Reagent for the Synthesis of Heterocycles
Authors: Vaitla Janakiram , Bayer Annette , Hopmann Kathrin H.
Published: April 2019

Sulfoxonium ylides have recently gained prominence as safe carbenoid precursors in metal-catalyzed reactions. The stability and reactivity of sulfoxonium ylides depend on the substitution of the ylide carbon. The reactivity of vinyl-substituted sulfoxonium ylides is different and offers several advantages over known stabilized sulfoxonium ylides in the case of carbenoid transfer reactions. Herein, we provide an overview of early efforts in this area, with particular emphasis on our own recent development of sulfoxonium ylide-derived vinyl carbenoid transformations for N-Heterocycles.

1 Introduction

2 Classification of Sulfoxonium Ylides

3 Synthesis of Vinyl Sulfoxonium Ylides

4 [3+2] Annulation of Vinyl Sulfoxonium Ylides

5 [4+1] Annulation of Vinyl Sulfoxonium Ylides

6 Conclusion
Synthesis and Photophysical Properties of 1,4-Dihydro-2H,5H-chromeno[4,3-d][1,3]oxazin-5-ones, and Derivatives Containing Tethered 1,2,3-Triazoles, from 4-Aminocoumarins
Authors: Dilelio Marina C. , Brites Nathan P. , Vieira Larissa A. , Iglesias Bernardo A. , Kaufman Teodoro S. , Silveira Claudio C.
Published: April 2019

A facile protocol for the unprecedented one-pot H2SO4-mediated hydroxymethylation/cyclative N,O-acetalization of 4-aminocoumarins to 1,4-dihydro-2H,5H-chromeno[4,3-d][1,3]oxazin-5-ones, in moderate to good yields, was developed and optimized. The scope and limitations of the transformation, which takes place in water or water/THF mixtures, were also studied. The nitrogen atom of the resulting tricycles was used to tether alkyl, aryl and 1,2,3-triazolylmethyl moieties, employing a two-step click chemistry approach for the latter. The photophysical properties of the heterocycles, as well as of their 1,2,3-triazole derivatives, were also examined. The N-aryl derivatives exhibited high quantum yields of fluorescence (up to Φf = 0.69) and very large Stokes shifts (up to 201 nm).
Neue Wege in der Aus- und Weiterbildung: Erfolgreiche Etablierung der eRef in der Niederösterreichischen Landeskliniken-Holding
Authors: Schindler Carola
Published: April 2019

Eine gute Ausbildung braucht gute Lehrer. Aber auch der schnelle, unkomplizierte Zugriff auf die richtigen Informationen ist entscheidend. Als Aus- und Weiterbilder hat er sich OA Dr. med. univ. Thomas Laschitz, MBA für die Einführung des medizinischen Wissensportals eRef im Klinikverbund der Niederösterreichischen Landeskliniken-Holding eingesetzt.
Effect of polarity on beam and plasma target formation in a dense plasma focus
Authors: Jiang S. , Higginson D. P. , Link A. , Holod I. , Schmidt A.
Published: April 2019

Dense plasma focus (DPF) devices are conventionally operated with a polarity such that the inner electrode (IE) is the anode. It has been found that interchanging the polarity of the electrodes (i.e., IE as the cathode) can cause an order of magnitude decrease in the neutron yield. This polarity riddle has previously been studied empirically through several experiments and is yet not well understood. We have performed kinetic simulations using the particle-in-cell modeling to investigate the problem. This is the first time that both polarities have been studied with simulations in great detail. In our simulations, we have modeled the entire beam and plasma target formation processes, but we did not consider differences in break-down conditions caused by the two polarities. We have found that when using reverse polarity ions are still accelerated and, in fact, attain similar energy spectra as in the standard polarity case. The difference is that the fields are flipped and thus ions are accelerated in the opposite direction. So, in the reverse polarity case, the majority of the “plasma target” (formed by the imploding plasma) is in the opposite direction of the beam, and thus, the beam hits the IE and produces few neutrons. With a better inner electrode configuration, reverse polarity is able to create a high-quality ion beam as well as a high-density target. Both can be comparable to that generated by standard polarity. Furthermore, we will show that it is easier to add an additional solid catcher target to a DPF device with reverse polarity, potentially enabling it to generate more neutrons than standard polarity.
Bacterial chromosome organization. I. Crucial role of release of topological constraints and molecular crowders
Authors: Agarwal Tejal , Manjunath G. P. , Habib Farhat , Chatterji Apratim
Published: April 2019

We showed in our previous studies that just 3% cross-links (CLs), at special points along the contour of the bacterial DNA, help the DNA-polymer to get organized at micron length scales [T. Agarwal et al., J. Phys.: Condens. Matter 30, 034003 (2018) and T. Agarwal et al., EPL (Europhys. Lett.) 121, 18004 (2018)]. In this work, we investigate how does the release of topological constraints help in the “organization” of the DNA-polymer. Furthermore, we show that the chain compaction induced by the crowded environment in the bacterial cytoplasm contributes to the organization of the DNA-polymer. We model the DNA chain as a flexible bead-spring ring polymer, where each bead represents 1000 base pairs. The specific positions of the CLs have been taken from the experimental contact maps of the bacteria Caulobacter crescentus and Escherichia coli. We introduce different extents of ease of release of topological constraints in our model by systematically changing the diameter of the monomer bead. It varies from the value where chain crossing can occur freely to the value where chain crossing is disallowed. We also study the role of compaction of the chain due to molecular crowders by introducing an “effective” weak Lennard-Jones attraction between the monomers. Using Monte Carlo simulations, we show that the release of topological constraints and the crowding environment play a crucial role to obtain a unique organization of the polymer.
Sampled grating terahertz quantum cascade lasers
Authors: Zhao Fang-yuan , Li Yuan-yuan , Liu Jun-qi , Liu Feng-qi , Zhang Jin-chuan , zhai Shen-qiang , Zhuo Ning , Wang Li-jun , Liu Shu-man , Wang Zhan-guo
Published: April 2019

We demonstrate a metal-stripe sampled Bragg grating distributed feedback terahertz quantum cascade laser for power scaling up along with reliable single-mode emission. The major advantage is that the effective coupling coefficient can be flexibly engineered by tuning the sampling duty cycle. With sampled grating technology, the single-mode peak power of 186 mW is realized in a pulsed operation at 10 K, which is approximately 1.35 times that of the uniform grating laser. Besides, the horizontal beam pattern is close to the Gaussian distribution with ideal beam quality.
Features of streamer formation in a sharply non-uniform electric field
Authors: Sorokin Dmitry A. , Tarasenko Victor F. , Beloplotov Dmitry V. , Lomaev Mikhail I.
Published: April 2019

The streamer formation in a point-to-plane gap filled with atmospheric-pressure air has been experimentally studied using a streak camera and a four-channel intensified charge-coupled device camera with simultaneously recording waveforms of voltage and discharge current pulses. A large diameter streamer was observed at various amplitudes of nanosecond voltage pulses. The instantaneous streamer velocity was measured using the streak camera. It was found that the streamer has a high velocity at the initial stage of development, but it rapidly decreases. The minimum streamer velocity corresponds to the maximum diameter. The streamer velocity increases again by an order of magnitude when it approaches the opposite electrode. It was found that the streamer velocity correlates with the value of a displacement current induced by its propagation. At the initial stage of the streamer development during subnanosecond breakdown, the displacement current can reach several kiloamperes; this is comparable to the conduction current after the breakdown.
Two-axis goniometer for single-crystal nuclear magnetic resonance measurements
Authors: Cvitanić Tonči , Lukas Marin , Grbić Mihael S.
Published: April 2019

We report the design and construction of a two-axis goniometer capable of any sample orientation with respect to the external magnetic field. The advantage of this design is that it allows free rotations around a single axis independent of the other which minimizes rotational error without reduction of the angle range. Goniometer is capable of operating with high precision at both low and high temperatures and in high magnetic fields. To test its performance, it was mounted on the custom made nuclear magnetic resonance probe for use in an Oxford Instruments wide-bore variable field superconducting magnet.
Nonlinear elastic behavior and anisotropic electronic properties of two-dimensional borophene
Authors: Faghihnasiri Mahdi , Jafari Homayoun , Ramazani Ali , Shabani Mostafa , Estalaki Sina Malakpour , Larson Ronald G.
Published: April 2019

Using first-principles density functional theory calculations, the mechanical and electronic properties of the three main (β12, χ3, and striped) phases of single-layer borophene sheets are calculated under in-plane uniaxial/biaxial strain, including the harmonic strain-energy regions of β12, χ3, and striped phases over the strain ranges of −3.5%–3.5%, −4.5%–4.5%, and −2.5%–2.5%, respectively, along the x direction (the direction of the highest bond orientation). We introduce a method by which the nonlinear behavior of these and any other two-dimensional materials can be investigated even above their ultimate strains, beyond which no-uniform plastic deformation occurs. Defining an appropriate deformation, and utilizing both continuum modeling and special equations based on the density functional theory, a method of computing second-, third-, and fourth-order elastic constants of the three different phases of borophene is presented that utilizes rectangular unit cells, which can substitute for any two-dimensional unit cell. Using this new method, 4 independent second-order, 6 third-order, and 9 fourth-order elastic constants are calculated, which is the complete set of elastic constants for two-dimensional structures. The electronic band structure of borophene shows anisotropic electronic behavior. Despite the metallic character of borophene sheets, applying directional strain based on deformation matrices creates a bandgap in some regions of the Brillouin zones, opening up the possibility of mechanical control of electronic properties.
Ion percolation through annealed, supported graphene oxide films: Role of nanochannels and voids
Authors: Ravishankar Vasumathy , Ramaprabhu S. , Jaiswal Manu
Published: April 2019

Graphene oxide (GO), an ionic and molecular sieve, is an important material for wide-spectrum filtration, since its properties can be tuned by controlling the structure and dimensions of nanochannels between GO nanosheets. In the literature, mechanisms of ion percolation have been proposed assuming GO to be a uniform structure of vertically stacked graphene sheets decorated with functional groups, termed as lamellae. However, in practice, GO is known to have a hierarchical microstructure. In the present work, supported GO films annealed at different temperatures have been studied with the aim of discerning the relative contributions of nanochannels and voids, gaps between the lamellae, using electro-impedance spectroscopy, and the results were fitted to equivalent circuits. Monotonous decrease in the charge transfer resistance Rct and an increase in the percolation resistance RP were observed for GO films annealed up to 160 °C. Increase in RP, taken in perspective with a gradual loss of ordering in nanosheets as observed from X-ray diffraction spectra, enables the conclusion that nanochannels are the dominant pathways of percolation. This was further confirmed by the response of GO films annealed at 180 °C and 200 °C, where a strong dynamic is observed. For these annealed GO films, charge transfer happens both in the conducting films and at the fluorine-doped tin oxide interface. The two processes of ion percolation and charge transfer are, however, interdependent, and are not separated in the impedance response.
High vacuum equipment for the measurement of the macroscopic dipole moment of polar molecular crystals
Authors: Hesterberg Rolf , Hulliger Jürg
Published: April 2019

Polar crystals placed into a charged plate capacitor may experience a mechanical torque. Mounting crystals on a spiral spring allows us to measure the momentum and thus the macroscopic dipole moment of a crystal object. To exclude the influence of ambient conditions (air, ions, electrons), experiments are performed in a high vacuum. Following text book knowledge, polar crystals show a surface charge density especially for faces involving the polar crystal axis. For ambient conditions, it is assumed that external charge carriers compensate the surface charge. Here, we present unique equipment by which the dipole moment of crystals can be measured also when the charge carrying parts of a crystal were cut off by two metallic blades. Present measurements for α-resorcinol (mm2) allow us to conclude that (a) as grown polar crystals measured under the high vacuum condition show a macroscopic dipole moment, (b) the weighted dipole moment increases after cutting the main polar faces, and (c) the weighted dipole moment decreased after exposure to ambient air.
Generalized Voigt broadening due to thermal fluctuations of electromechanical nanosensors and molecular electronic junctions
Authors: Ochoa Maicol A. , Zwolak Michael
Published: April 2019

Graphene and other 2D materials give a platform for electromechanical sensing of biomolecules in aqueous, room temperature environments. The electronic current changes in response to mechanical deflection, indicating the presence of forces due to interactions with, e.g., molecular species. We develop illustrative models of these sensors in order to give explicit, compact expressions for the current and signal-to-noise ratio. Electromechanical structures have an electron transmission function that follows a generalized Voigt profile, with thermal fluctuations giving a Gaussian smearing analogous to thermal Doppler broadening in solution/gas-phase spectroscopic applications. The Lorentzian component of the profile comes from the contact to the electrodes. After providing an accurate approximate form of this profile, we calculate the mechanical susceptibility for a representative two-level bridge and the current fluctuations for electromechanical detection. These results give the underlying mechanics of electromechanical sensing in more complex scenarios, such as graphene deflectometry.
Spatial and thermal signatures of α and β relaxations in glassy and glacial aliphatic ionic liquids
Authors: Lima Thamires A. , Li Zhixia , Tyagi Madhusudan , Ribeiro Mauro C. C. , Z Y
Published: April 2019

The competition between Coulomb and van der Waals interactions brings forth unique dynamic features and broad applications to ionic liquids. Herein, we present a combined calorimetric, X-ray diffraction, incoherent elastic, and quasi-elastic neutron scattering study, over a wide temperature range (180–340 K), of the relaxational dynamics of the liquid, supercooled liquid, crystalline, glassy, and glacial states of two model ionic liquids: tributylmethylammonium (a good glass-former) and butyltrimethylammonium (a good crystal-former) cations and the bis(trifluoromethanesulfonyl)imide anion. In both systems, we observed two distinct relaxation processes. The Q-dependence of the respective relaxation time shows that the α-process is diffusive, while the β-process is modulated by the structure of the liquids.
In-situ characterization of O-terminated Cu tips for high-resolution atomic force microscopy
Authors: Liebig Alexander , Giessibl Franz J.
Published: April 2019

Functionalizing a metal tip with a single CO molecule (CO tip) leads to an unprecedented spatial resolution of small organic molecules by frequency-modulation atomic force microscopy (FM-AFM) at low temperatures. O-terminated Cu tips (CuOx tips) show comparable imaging capabilities as CO tips but exhibit a much stiffer apex. So far, to verify tip functionalization with oxygen (i.e., CuOx tips), scanning tunneling microscopy and AFM images, together with force spectroscopy curves of copper oxide domains, have been compared with calculated data for different tip models. Here, we apply the carbon-monoxide front atom identification (COFI) method and additional force spectroscopy to characterize CuOx tips in-situ on a Cu(110) surface. In COFI, a single CO molecule adsorbed on a Cu surface is imaged to atomically resolve the tip apex. Based on our findings, we suggest accompanying tip fingerprinting with COFI and force spectroscopy to identify the atomic and chemical compositions of the apex of CuOx tips for high-resolution AFM experiments.
Phase separation and emergence of collective motion in a one-dimensional system of active particles
Authors: Barberis Lucas , Peruani Fernando
Published: April 2019

We study numerically a one-dimensional system of self-propelled particles, where the state of the particles is given by their moving direction (left or right), which is encoded by a spin-like variable, and their position. Particles interact by short-ranged, spring-like attractive forces and do not possess spin-spin interactions (i.e., velocity alignment). Newton’s third law is broken in this model by assuming an asymmetric interaction range that is larger in the direction of the moving direction of the particle. We show that in this nonequilibrium system, due to the absence of the action-reaction symmetry, there exists an intimate link between phase separation and the formation of highly coherent, spatially localized, moving flocks (i.e., collective motion). More specifically, we prove the existence of two fundamentally different types of active phase separation, which we refer to as neutral phase separation (NPS) and polar phase separation. Furthermore, we indicate that NPS is subdivided in two classes with distinct critical exponents. These results are of key importance to understand that in active matter, there exist several phase-separation classes and that the emergence of polar, self-organized patterns (i.e., flocks) does not require the presence of a velocity alignment.
Influence of film thickness on the stability of free-standing Lennard-Jones fluid films
Authors: Rivera José L. , Douglas Jack F.
Published: April 2019

Molecular dynamics simulations of thin free-standing Lennard-Jones fluid films were carried out with a view of establishing the thickness range over which such films are thermodynamically stable. Thermophysical and interfacial properties were studied as a function of film thickness, and we found that free-standing films at 116 K are no longer stable below a critical film thickness of about 3.3 nm in laboratory units appropriate for methane. In particular, films having a smaller thickness than this critical value collapsed to form spherical droplets. Although the size of our simulated system affects the thickness of the layers and the corresponding thickness of the interface and the densities of coexisting phases, the estimated surface tension was found to be remarkably insensitive to finite size effects. We also found that the standard deviation of the surface tension diminished with an increasing size of the simulation cell in the interfacial plane. However, these finite size effects do not alter the order of magnitude of the predicted critical film thickness and our qualitative conclusion that the surface tension is relatively insensitive to film thickness in these model thin films.
Anisotropic phonon properties and effective electron mass in α-Ga2O3
Authors: Feneberg Martin , Bläsing Jürgen , Sekiyama Takahito , Ota Katsuya , Akaiwa Kazuaki , Ichino Kunio , Goldhahn Rüdiger
Published: April 2019

The ordinary and extraordinary infrared dielectric functions of α-Ga2O3 thin films with the corundum structure were investigated. The films were grown by mist chemical vapor epitaxy on (101¯0) sapphire substrates in (101¯0) surface orientation. They were doped by the donor tin with the resulting free-electron concentrations between 1017 and 1019 cm−3. Structural characterization revealed the absence of strain and the high crystallographic quality of the samples. It allows one to resolve all 7 Raman modes. 5 out of 6 infrared active transverse optical phonon modes lie in the investigated wave number range >250 cm−1, and are unambiguously identified by spectroscopic ellipsometry. For the highest doped sample, the free-carrier contribution (plasmon) to the infrared spectra allowed accurate determination of effective electron masses. They are m⊥*=(0.297±0.010)m0 (perpendicular to [0001]) and m||*=(0.316±0.007)m0 (parallel to [0001]) for an electron concentration of n = 1.1 × 1019 cm−3.
Molecular dynamics simulations of nano-confined methanol and methanol-water mixtures between infinite graphite plates: Structure and dynamics
Authors: Mosaddeghi Hamid , Alavi Saman , Kowsari Mohammad H. , Najafi Bijan , Az’hari Sara , Afshar Yaser
Published: April 2019

Molecular dynamics simulations are used to investigate microscopic structures and dynamics of methanol and methanol-water binary mixture films confined between hydrophobic infinite parallel graphite plate slits with widths, H, in the range of 7–20 Å at 300 K. The initial geometric densities of the liquids were chosen to be the same as bulk methanol at the same temperature. For the two narrowest slit widths, two smaller initial densities were also considered. For the nano-confined system with H = 7 Å and high pressure, a solid-like hexagonal arrangement of methanol molecules arranged perpendicular to the plates is observed which reflects the closest packing of the molecules and partially mirrors the structure of the underlying graphite structure. At lower pressures and for larger slit widths, in the contact layer, the methanol molecules prefer having the C–O bond oriented parallel to the walls. Layered structures of methanol parallel to the wall were observed, with contact layers and additional numbers of central layers depending on the particular slit width. For methanol–water mixtures, simulations of solutions with different composition were performed between infinite graphite slits with H = 10 and 20 Å at 300 K. For the nanoslit with H = 10 Å, in the solution mixtures, three layers of molecules form, but for all mole fractions of methanol, methanol molecules are excluded from the central fluid layer. In the nanopore with H = 20 Å, more than three fluid layers are formed and methanol concentrations are enhanced near the confining plates walls compared to the average solution stoichiometry. The self-diffusion coefficients of methanol and water molecules in the solution show strong dependence on the solution concentration. The solution mole fractions with minimal diffusivity are the same in confined and non-confined bulk methanol-water mixtures.
Possible mechanisms for degradation of photo induced micro actuation effect in a ferromagnetic shape memory alloy at high temperatures
Authors: Bagchi Abhishek , Sarkar Suman , Bysakh Sandip , Sarkar Susenjit , Mukhopadhyay P. K.
Published: April 2019

Ferromagnetic shape memory alloys (FSMAs) have been in active research nowadays for their unique properties of responses to both temperature changes and external magnetic fields. Recently, one such material, a CoNiAl based system, showed a photoinduced microactuation (PIMA) effect in which an incident spot of a tiny laser beam could induce actuation in these systems. This is unparalleled in ordinary materials, and its real cause is yet to be found. However, we tried to still use it in real world engineering applications, and for that, the limitations on its usability should be found. With this idea, we studied here in detail the effect of continuous degradation of the PIMA effect on a ribbon sample through TEM, as it was exposed to higher temperatures from room temperature. While the as-spun alloy had microstructured B2 ordered (Ni, Co)-Al micrometer sized grains embedded in a continuous L12 ordered cobalt-rich matrix channel, at 400 °C where the PIMA effect was fully destroyed, Co-rich nanosized precipitates were found to have formed inside the B2 grains, the actual FSMA component in the sample, and these are also found to have been oxidized. Concurrent oxidation studies showed the formation of an irregular shaped composite oxide layer with a thickness of about several hundred nanometers at the top surface. These are possibly the reasons behind the hindrance in the actuating motion. This was corroborated by magnetic studies also.
Flow instability in weakly eccentric annuli
Authors: Moradi H. V. , Tavoularis S.
Published: April 2019

A temporal linear stability analysis of laminar flow in weakly eccentric annular channels has been performed. It has been shown that, even for eccentricities ε and Reynolds numbers that were much smaller than those considered in previous studies, flow instability occurred in the form of travelling waves having characteristics that are very different from those of Tollmien-Schlichting waves and which were triggered at mid-gap by an inviscid mechanism that is associated with the presence of inflection points in azimuthal profiles of the base velocity. The critical stability conditions have been determined for 0 ≤ ε ≤ 0.1 and for diameter ratios 0 < γ < 1. The critical Reynolds number Rec decreased with increasing γ for 0 < γ ≲ 0.13, reached a minimum at γ ≈ 0.13, and increased with further increase in γ. The lowest observed Rec was 529 and occurred for ε = 0.1 and γ ≈ 0.13. As ε → 0, Rec ∝ ε−2. The critical wave number and the critical frequency of the disturbances decreased with increasing γ and approached zero as γ → 1, whilst their ratio was nearly constant in the range of parameters considered in this study. The most unstable regions were found to be at roughly mid-gap on the two flanks of the annulus, and the phase speed of the disturbances was close to the base flow velocity at these regions.
Evaluation of the exothermicity of the chemi-ionization reaction Nd + O → NdO+ + e− and neodymium oxide, carbide, dioxide, and carbonyl cation bond energies
Authors: Ghiassee Maryam , Kim JungSoo , Armentrout P. B.
Published: April 2019

The exothermicity of the chemi-ionization reaction, Nd + O → NdO+ + e−, has been indirectly determined by measuring the thermochemistry for reactions of the lanthanide metal neodymium cation (Nd+) with O2, CO2, and CO and reactions of NdO+ with CO, O2, and Xe. Guided ion beam tandem mass spectrometry was used to measure the kinetic energy dependent product ion cross sections for these reactions. NdO+ is formed through a barrierless exothermic process when the atomic metal cation reacts with O2 and CO2. All other reactions are observed to be endothermic. Analyses of the kinetic energy dependences of these cross sections yield 0 K bond dissociation energies (BDEs) for several species. The 0 K BDE for Nd+–O is determined to be 7.28 ± 0.10 eV from the average of four independent thresholds. This value is combined with the well-established Nd ionization energy to indicate an exothermicity of the title reaction of 1.76 ± 0.10 eV, which is lower and more precise than literature values. In addition, the Nd+–C, ONd+–O, and Nd+–CO BDEs are determined to be 2.61 ± 0.30, 2.12 ± 0.30, and 0.30 ± 0.21 eV. Additionally, theoretical BDEs of Nd+–O, Nd+–C, ONd+–O, and Nd+–CO are calculated at several levels for comparison with the experimental values. B3LYP calculations seriously underestimate the Nd+–O BDE, whereas MP2 and coupled-cluster with single, double-and perturbative triple excitations values are in reasonable agreement. Good agreement is generally obtained for Nd+–C, ONd+–O, and Nd+–CO BDEs as well.
Penetration of liquid droplets into hydrophobic fibrous materials under enhanced gravity
Authors: Jamali M. , Vahedi Tafreshi H. , Pourdeyhimi B.
Published: April 2019

In this paper, experimental and numerical simulations were devised to study and formulate the force required for forcing a droplet to penetrate into a thin nonwetting fibrous structure. Due to the complexity of the problem at hand, we considered only thin fibrous structures comprised of parallel or orthogonally layered fibers. The experiments were conducted using ferrofluid droplets placed on electrospun polystyrene fibrous coatings. A permanent magnet was used to apply a body force to the droplets from below, and the assembly was placed on a sensitive scale for measuring the applied force. Numerical simulations were conducted using the Surface Evolver finite element code validated through comparison with dedicated experimental results. We studied how the force needed to initiate droplet spontaneous penetration into a thin fibrous coating varies with varying the volume of the droplet or the geometric properties of the coating. Using a combination of simulation results and experimental observations, easy-to-use but approximate expressions were derived and used to predict the force required to initiate droplet spontaneous penetration into the above-mentioned fibrous material. These analytical expressions allow one to circumvent the need for running a numerical simulation for each and every droplet–coating combination of interest and thereby expand the application of our work to conditions different from those considered here.
Stochastic bursting in unidirectionally delay-coupled noisy excitable systems
Authors: Zheng Chunming , Pikovsky Arkady
Published: April 2019

We show that “stochastic bursting” is observed in a ring of unidirectional delay-coupled noisy excitable systems, thanks to the combinational action of time-delayed coupling and noise. Under the approximation of timescale separation, i.e., when the time delays in each connection are much larger than the characteristic duration of the spikes, the observed rather coherent spike pattern can be described by an idealized coupled point process with a leader–follower relationship. We derive analytically the statistics of the spikes in each unit, the pairwise correlations between any two units, and the spectrum of the total output from the network. Theory is in good agreement with the simulations with a network of theta-neurons.
Redefining bilingualism as a spectrum of experiences that differentially affects brain structure and function
Authors: DeLuca Vincent , Rothman Jason , Bialystok Ellen , Pliatsikas Christos
Published: April 2019

Learning and using an additional language is shown to have an impact on the structure and function of the brain, including in regions involved in cognitive control and the connections between them. However, the available evidence remains variable in terms of the localization, extent, and trajectory of these effects. Variability likely stems from the fact that bilingualism has been routinely operationalized as a categorical variable (bilingual/monolingual), whereas it is a complex and dynamic experience with a number of potentially deterministic factors affecting neural plasticity. Here we present a study investigating the combined effects of experience-based factors (EBFs) in bilingual language use on brain structure and functional connectivity. EBFs include an array of measures of everyday usage of a second language in different types of immersive settings (e.g., amount of use in social settings). Analyses reveal specific adaptations in the brain, both structural and functional, correlated to individual EBFs and their combined effects. Taken together, the data show that the brain adapts to be maximally efficient in the processing and control of two languages, although modulated ultimately by individual language experience.
Regenerative therapy based on miRNA-302 mimics for enhancing host recovery from pneumonia caused by
Streptococcus pneumoniae
Authors: Wang Yan , Li Yong , Zhang Peggy , Baker Sandy T. , Wolfson Marla R. , Weiser Jeffrey N. , Tian Ying , Shen Hao
Published: April 2019

Significance

Our results provide an example of reactivation of a signaling pathway important in embryogenesis that can be exploited to promote tissue repair and help host recovery from bacterial pneumonia. Although this approach of regenerative medicine will not curtail infection per se, it reduces suffering and shortens recovery time by fostering tissue repair, thus complementing antibiotic treatment and improving patient outcomes from serious infections. Our findings open up a frontier in the treatment of microbial infections using microRNA-based regenerative therapy.
Necroptosis mediators RIPK3 and MLKL suppress intracellular Listeria replication independently of host cell killing
Authors: Sai Kazuhito , Parsons Cameron , House John S. , Kathariou Sophia , Ninomiya-Tsuji Jun
Published: April 2019

RIPK3, a key mediator of necroptosis, has been implicated in the host defense against viral infection primary in immune cells. However, gene expression analysis revealed that RIPK3 is abundantly expressed not only in immune organs but also in the gastrointestinal tract, particularly in the small intestine. We found that orally inoculated Listeria monocytogenes, a bacterial foodborne pathogen, efficiently spread and caused systemic infection in Ripk3-deficient mice while almost no dissemination was observed in wild-type mice. Listeria infection activated the RIPK3-MLKL pathway in cultured cells, which resulted in suppression of intracellular replication of Listeria. Surprisingly, Listeria infection–induced phosphorylation of MLKL did not result in host cell killing. We found that MLKL directly binds to Listeria and inhibits their replication in the cytosol. Our findings have revealed a novel functional role of the RIPK3-MLKL pathway in nonimmune cell-derived host defense against Listeria invasion, which is mediated through cell death–independent mechanisms.
Review of Manual for Survival by Kate Brown
Authors: Smith Jim
Published: April 2019

My review, based on nearly thirty years of research on Chernobyl and dozens of visits to the contaminated areas of Belarus, Ukraine and Russia, argues that Manual for Survival ignores the thousands of scientific studies on Chernobyl which are available in the international scientific literature. In doing so, it presents a biased and misleading account of the health and environmental effects of the accident. I believe that this book only perpetuates the many myths about the accident effects and has very little basis in sound science.
Bounding the average gate fidelity of composite channels using the unitarity
Authors: Carignan-Dugas Arnaud , Wallman Joel J , Emerson Joseph
Published: April 2019

There is currently a significant need for robust and efficient methods for characterizing quantum devices. While there has been significant progress in this direction, there remains a crucial need to precisely determine the strength and type of errors on individual gate operations, in order to assess and improve control as well as reliably bound the total error in a quantum circuit given some partial information about the errors on the components. In this work, we first provide an optimal bound on the total fidelity of a circuit in terms of component fidelities, which can be efficiently experimentally estimated via randomized benchmarking (RB). We then derive a tighter bound that applies under additional information about the coherence of the error, namely, the unitarity, which can also be estimated via a related experimental protocol. This improved bound smoothly interpolates between the worst-case quadratic and best-case linear scaling for composite error channels. As an application we show how our analysis substantially improves the achievable precision on estimates of the infidelities of individual gates under interleaved RB, enabling greater precision for current experimental methods to assess and tune-up control over quantum gate operations.
Relativistic short-pulse high harmonic generation at 1.3 and 2.1 μm wavelengths
Authors: Beier N , Nguyen T , Lin J , Nees J , Krushelnick K , Dollar F
Published: April 2019

While nearly all investigations of high order harmonic generation with relativistically intense laser pulses have taken place at 800 or 1053 nm, very few experimental studies have been done at other wavelengths. In this study, we investigate the scaling of relativistic high harmonic generation towards longer wavelengths at intensities of a
0 ∼ 1. Longer driver wavelengths enable enhanced diagnostics of the harmonic emission, as multiple orders lie in the optical regime. We measure the conversion efficiency by collecting the entire harmonic emission as well as the divergence through direct imaging. We compare the emission with 2D particle-in-cell simulations to determine the experimental target conditions. This new regime of high order harmonic generation also enables relativistic scaling as well as improved discrimination of harmonic generation mechanisms.
Contact transparency in mechanically assembled 2D material devices
Authors: Mills Scott , Mizuno Naomi , Wang Peng , Lyu Jian , Watanabe Kenji , Taniguchi Takashi , Camino Fernando , Zhang Liyuan , Du Xu
Published: April 2019

Two-dimensional atomic crystals (2DACs) can be mechanically assembled with precision for the fabrication of heterostructures, allowing for the combination of material building blocks with great flexibility. In addition, while conventional nanolithography can be detrimental to most of the 2DACs which are not sufficiently inert, mechanical assembly potentially minimizes the nanofabrication processing and preserves the intrinsic physical properties of the 2DACs. In this work we study the interfacial charge transport between various 2DACs and electrical contacts, by fabricating and characterizing 2DAC-superconductor junctions through mechanical transfer. Compared to devices fabricated with conventional nanolithography, mechanically assembled devices show comparable or better interface transparency. Surface roughness at the electrical contacts is identified to be a major limitation to the interface quality.
Remarks on a fractional-time stochastic equation
Authors: Foondun Mohammud
Published: April 2019

We consider a class of a fractional-time stochastic equation defined on a bounded domain and show that the presence of the time derivative induces a significant change in the qualitative behaviour of the solutions. This is in sharp contrast with the phenomenon showcased in [ALEA Lat. Am. J. Probab. Math. Stat. 12 (2015), pp. 551–571] and extented in [Stochastic Process Appl. 126 (2016), pp. 1184–1205] and [Electron. Commun. Probab. 23 (2018)]. We also show that as one tunes off the fractional in the fractional time derivative, the solution behaves more and more like its usual counterpart.
Sharp gradient estimates for a heat equation in Riemannian manifolds
Authors: Dung Ha , Dung Nguyen
Published: April 2019

In this paper, we prove sharp gradient estimates for a positive solution to the heat equation

u
t

=
Δ
u
+
a
u
log
⁡
u

u_t=\Delta u+au\log u

in complete noncompact Riemannian manifolds. As its application, we show that if

u
u

is a positive solution of the equation

u
t

=
Δ
u

u_t=\Delta u

and

log
⁡
u

\log u

is of sublinear growth in both spatial and time directions, then

u
u

must be constant. This gradient estimate is sharp since it is well known that

u
(
x
,
t
)
=

e

x
+
t

u(x,t)=e^{x+t}

satisfying

u
t

=
Δ
u

u_t=\Delta u

.
Holomorphic Borcherds products of singular weight for simple lattices of arbitrary level
Authors: Opitz Sebastian , Schwagenscheidt Markus
Published: April 2019

We classify the holomorphic Borcherds products of singular weight for all simple lattices of signature

(
2
,
n
)

(2,n)

with

n
≥
3

n \geq 3

. In addition to the automorphic products of singular weight for the simple lattices of square free level found by Dittmann, Hagemeier, and the second author, we obtain several automorphic products of singular weight

1

/

2

1/2

for simple lattices of signature

(
2
,
3
)

(2,3)

. We interpret them as Siegel modular forms of genus

2
2

and explicitly describe them in terms of the ten even theta constants. In order to rule out further holomorphic Borcherds products of singular weight, we derive estimates for the Fourier coefficients of vector valued Eisenstein series, which are of independent interest.
Mixed volumes and the Bochner method
Authors: Shenfeld Yair , van Handel Ramon
Published: April 2019

At the heart of convex geometry lies the observation that the volume of convex bodies behaves as a polynomial. Many geometric inequalities may be expressed in terms of the coefficients of this polynomial, called mixed volumes. Among the deepest results of this theory is the Alexandrov-Fenchel inequality, which subsumes many known inequalities as special cases. The aim of this note is to give new proofs of the Alexandrov-Fenchel inequality and of its matrix counterpart, Alexandrov’s inequality for mixed discriminants, that appear conceptually and technically simpler than earlier proofs and clarify the underlying structure. Our main observation is that these inequalities can be reduced by the spectral theorem to certain trivial “Bochner formulas”.
N-glycosylation–dependent regulation of hK2P17.1 currents
Authors: Wiedmann Felix , Schlund Daniel , Voigt Niels , Ratte Antonius , Kraft Manuel , Katus Hugo A. , Schmidt Constanze
Published: April 2019

Two pore-domain potassium (K2P) channels mediate potassium background currents that stabilize the resting membrane potential and facilitate action potential repolarization. In the human heart, hK2P17.1 channels are predominantly expressed in the atria and Purkinje cells. Reduced atrial hK2P17.1 protein levels were described in patients with atrial fibrillation or heart failure. Genetic alterations in hK2P17.1 were associated with cardiac conduction disorders. Little is known about posttranslational modifications of hK2P17.1. Here, we characterized glycosylation of hK2P17.1 and investigated how glycosylation alters its surface expression and activity. Wild-type hK2P17.1 channels and channels lacking specific glycosylation sites were expressed in Xenopus laevis oocytes, HEK-293T cells, and HeLa cells. N-glycosylation was disrupted using N-glycosidase F and tunicamycin. hK2P17.1 expression and activity were assessed using immunoblot analysis and a two-electrode voltage clamp technique. Channel subunits of hK2P17.1 harbor two functional N-glycosylation sites at positions N65 and N94. In hemi-glycosylated hK2P17.1 channels, functionality and membrane trafficking remain preserved. Disruption of both N-glycosylation sites results in loss of hK2P17.1 currents, presumably caused by impaired surface expression. This study confirms diglycosylation of hK2P17.1 channel subunits and its pivotal role in cell-surface targeting. Our findings underline the functional relevance of N-glycosylation in biogenesis and membrane trafficking of ion channels.
Adult-Life Alcohol Consumption and Age-Related Cognitive Decline from Early Adulthood to Late Midlife
Authors: Grønkjær Marie , Flensborg-Madsen Trine , Osler Merete , Sørensen Holger J , Becker Ulrik , Mortensen Erik L
Published: April 2019

Aims

Alcohol consumption is a modifiable and plausible risk factor for age-related cognitive decline but more longitudinal studies investigating the association are needed. Our aims were to estimate associations of adult-life alcohol consumption and consumption patterns with age-related cognitive decline.

Methods

We investigated the associations of self-reported adult-life weekly alcohol consumption and weekly extreme binge drinking (≥10 units on the same occasion) with changes in test scores on an identical validated test of intelligence completed in early adulthood and late midlife in 2498 Danish men from the Lifestyle and Cognition Follow-up study 2015. Analyses were adjusted for year of birth, retest interval, baseline IQ, education and smoking.

Results

Men with adult-life alcohol consumption of more than 28 units/week had a larger decline in IQ scores from early adulthood to late midlife than men consuming 1–14 units/week (B29–35units/week = −3.6; P < 0.001). Likewise, a 1-year increase in weekly extreme binge drinking was associated with a 0.12-point decline in IQ scores (P < 0.001). Weekly extreme binge drinking explained more variance in IQ changes than average weekly consumption. In analyses including mutual adjustment of weekly extreme binge drinking and average weekly alcohol consumption, the estimated IQ decline associated with extreme binge drinking was largely unaffected, whereas the association with weekly alcohol consumption became non-significant.

Conclusions

Adult-life heavy alcohol consumption and extreme binge drinking appear to be associated with larger cognitive decline in men. Moreover, extreme binge drinking may be more important than weekly alcohol consumption in relation to cognitive decline.