bluuebunny/crossref_metadata_2025 huggingface dataset:
DNA origami-based microtubule analogue
Authors: Zhang Tao
Published: August 2020

A microtubule hollow structure is one type of cytoskeletons which directs a number of important cellular functions. When recapitulating biological events in a cell-free system, artificial frames are often required to execute similar cytoskeletal functions in synthetic systems. Here, I report a prototypical microtubular assembly using a DNA origami nanostructuring method. Through structural design at the molecular level, 32HB (helices bundle)-based DNA origami objects can form micrometers long tubular structures via shape-complementary side patterns engagement and head-to-tail blunt-end stacking. Multiple parameters have been investigated to gain optimized polymerization conditions. Conformational change with an open vs closed hinge is also included, rendering conformational changes for a dynamic assembly. When implementing further improved external regulation with DNA dynamics (DNA strand displacement reactions or using other switchable non-canonical DNA secondary structures) or chemical stimuli, the DNA origami-based microtubule analogue will have great potential to assemble and disassemble on purpose and conduct significantly complicated cytoskeletal tasks in vitro.
Magnetron sputtering: determining scaling relations towards real power discharges using 3D particle-in-cell Monte Carlo models
Authors: Tonneau R , Pflug A , Lucas S
Published: August 2020

Plasma simulation of glow-magnetized discharges with the particle-in-cell Monte Carlo (PICMC) method is constraint to low current densities because of otherwise huge computational requirements. The present work aims to show, how it is nevertheless possible to extrapolate information for higher current densities similar to realistic lab or industrial conditions by applying a scaling strategy on the simulation. This is demonstrated for a DC magnetron sputtering (DCMS) case study involving the following species: Ar, Ar+, Ti, Ti+ and electrons. The evolution of the electron density is extracted from the simulation and compared with experimental values obtained with a Langmuir probe. A linear relationship between the electron density and the discharge current is highlighted and explained by studying the reaction rates of both ionization and excitation collisions. This allows to scale the reaction rates with the discharge parameters: the Ar-electron impact ionization and excitation rates scale linearly with the discharge current, while the electron impact ionization rate of sputtered species scales quadratically with the discharge current. The simulations also feature propagating plasma instabilities, so-called spokes, but in average, the above-mentioned scaling laws hold. Consequently, the flux of particles at the substrate during a plasma deposition process at realistic power density can be extrapolated from a 3D PICMC simulation at lower power density. Finally, the validity domain of the scaling strategy is discussed in the light of the model constraints.
Symbolic finite element discretization and model order reduction of a multiphysics model for IPMC sensors
Authors: Kondo Kota , Takagi Kentaro , Zhu Zicai , Asaka Kinji
Published: August 2020

The multiphysics model of ionic polymer-metal composite (IPMC) sensors proposed by Zhu has a significant advantage of being able to describe the dynamic sensor response, which highly depends on humidity, by explicitly considering solvent dynamics. However, it is difficult to perform analysis and simulation because Zhu’s model is represented by complex non-linear partial differential equations. This paper describes the symbolic finite element discretization of Zhu’s model and further discusses the essential dynamics of the reduced-order model extracted from the finite element model. The obtained linear ordinary differential equations, or the state equation, can be easily implemented in simulators via common programming languages. The simulation results of an in-house simulator implemented by MATLAB code show good agreement with those of direct numerical simulation by using commercial software, COMSOL. To further simplify the model, the minimum order required for an appropriate approximation is numerically investigated by using a model order reduction technique. This paper reveals that the dynamic response of an IPMC sensor can be consequently approximated by a first-order or second-order linear time-invariant system.
A novel piezoelectric linear actuator designed by imitating skateboarding movement
Authors: Wang Kuifeng , Li Xuan , Sun Wuxiang , Yang Zhixin , Liang Tianwei , Huang Hu
Published: August 2020

By imitating skateboarding movement, a novel stick–slip piezoelectric linear actuator was proposed in this study. A specific flexure driving foot mechanism (FDFM) was designed to realize the bionic driving function, and theoretical analysis was conducted to calculate the displacement amplification ratio of the FDFM which was further confirmed by finite element simulation. Being different from most of previous design that the slider moved and the driving mechanism was fixed, here the FDFM was integrated with the slider and they moved together along the guide rail. Being similar to that the train moved along the tracks, this kind of layout would facilitate the realization of larger working stroke of the actuator. By experiments, output characteristics of the designed actuator under various driving frequencies and voltages were tested. The results showed that by changing the waveform of driving voltage, both forward and reverse motions with good linearity and stability could be easily achieved. The speed of reverse motion was higher than that of forward motion because of the relatively larger backward motion during forward motion, which was due to the promotion of deformation recovery of the FDFM. Furthermore, the resolution and loading capacity were characterized. The resolutions of forward and reverse motions were 47 nm and 45 nm, respectively, and the actuator could achieve a relatively stable speed when the vertical load was in the range of 0–2 N. This study is expected to provide a new idea for designing piezoelectric actuators with features of high speed, high stability and large working stroke.
Joint characteristics of ultrasonic welded CC bridge joints for HTS coil applications
Authors: Shin Hyung-Seop , Jung Chan-Hun , Nisay Arman Ray
Published: August 2020

Long lengths of second-generation REBCO coated conductor (CC) tapes must be joined together when power cables, coils, and magnets requiring kilometer-scale lengths are fabricated. Various resistive joining techniques of CC tapes, such as soldering and diffusion reaction, have been studied. The joint method should provide good adhesion, low joint resistance (R
j), no critical current (I
c) degradation, cost effectiveness, and simplicity in processing. An ultrasonic welding (UW) process was developed and used to form various types of CC joint structures, such as lap- and butt-joints, using differently stabilized REBCO CC tapes. In this study, the UW process was used to form various bridge-joints of CC tapes for high-temperature superconducting coils. A mechanical-controlled soldering method which has provided a low contact resistance was also adopted for comparison. CC joints of various structures were fabricated using UW and soldering, and the retained I
c and R
j were measured at 77 K and self-field in each. The electromechanical properties of the CC bridge-joints were evaluated using a bending test. Results showed that R
j varied in the CC joints depending on the structure type and joint area. Moreover, the additional Sn layer in Cu-stabilized CC tapes improved R
j in each joint structure because it provided a solder-like bond at the joint interface. The bridge-joints formed using UW showed comparable bending diameter tolerances for irreversible I
c degradation to those formed using mechanically controlled soldering. The multiple 4 mm wide CC bridges provided more flexibility at the joint part due to gaps between bridges and resulted to a better tolerance to tension bending than the single 12 mm wide ones.
Vortex phase diagram in 12442-type RbCa2Fe4As4F2 single crystal revealed by magneto-transport and magnetization measurements
Authors: Xing Xiangzhuo , Yi Xiaolei , Li Meng , Meng Yan , Mu Gang , Ge Jun-Yi , Shi Zhixiang
Published: August 2020

The recently discovered 12442-type ACa2Fe4As4F2 (A = K, Rb, Cs) compounds are the only iron-based superconductors (IBSs) with double FeAs layers between neighboring insulating layers, analogous to the double CuO2 layers in some high-T
c cuprates. Here, we report the study of vortex phase diagram of RbCa2Fe4As4F2 single crystal via magneto-transport and magnetization measurements. The resistive transition under magnetic fields shows a foot-like kink at a characteristic temperature, T
s, followed by a resistive tail in nearly zero resistivity region. Such behavior is ascribed to a vortex slush transition at T
s, below which the vortex state has short-range vortex lattice correlation, and then a second-order transition into the vortex glass phase occurs with further decreasing temperature. Above T
s, the Arrhenius plot of resistivity shows two linear regions that are separated by a crossover line T
cr(B), which is associated with a crossover from collective to plastic pinning or different flux pinning behaviors resulted from different types of defect. In addition, the magnetic hysteresis loops reveal a second magnetization peak (SMP), which is shifted to lower fields with increasing temperature for T< 12 K. However, the SMP unexpectedly moves back to a higher field at T= 12 K, and then gradually turns into a shoulder or kink that moves to higher fields at high temperatures, such anomalous behavior has never been observed in IBSs. According to the magneto-transport and magnetization data, the vortex phase diagram of RbCa2Fe4As4F2 is finally constructed. Details on the different vortex phase transitions and relevant physical scenarios are given and discussed.
Quasiclassical approach to synergic synchrotron–Cherenkov radiation in polarized vacuum
Authors: Artemenko I I , Nerush E N , Kostyukov I Yu
Published: August 2020

Photon emission by an ultrarelativistic charged particle in extremely strong magnetic field is analyzed, with vacuum polarization and photon recoil taken into account. Vacuum polarization is treated phenomenologically via refractive index. The photon emission occurs in the synergic (cooperative) synchrotron–Cherenkov process [J Schwinger et al 1976 Annals of Physics
96 303] which is similar to the synchrotron emission rather than to the Cherenkov one. For electrons, the effect of vacuum polarization on the emission spectrum is not evident at least below the probable onset of non-perturbative quantum electrodynamics (QED). However, the effect of vacuum polarization on the emission spectrum can be observable for muons already at γB/B

S
≈ 30, with γ the muon Lorentz factor, B the magnetic field strength and B

S
the critical QED field. Nevertheless, vacuum polarization leads to only 10% enhancement of the maximum of the radiation spectrum.
Holographic technicolor model and dark matter *
Authors: Chen Yidian , Bi Xiao-Jun , Huang Mei
Published: August 2020

We investigate the strongly coupled minimal walking technicolor model (MWT) in the framework of a bottom-up holographic model, where the global SU(4) symmetry breaks into

subgroups. In the holographic model, we found that 125 GeV composite Higgs particles and small Peskin–Takeuchi S parameter can be achieved simultaneously. In addition, the model predicts a large number of particles at the TeV scale, including dark matter candidates Technicolor Interacting Massive Particles (TIMPs). If we consider the dark matter nuclear spin-independent cross-section in the range of

, which can be detected by future experiments, the mass range of TIMPs predicted by the holographic technicolor model is

TeV.
Gluon-pair-creation production model of strong interaction vertices *
Authors: Wan Bing-Dong , Qiao Cong-Feng
Published: August 2020

By studying the

exclusive decay to double glueballs, we introduce a model to phenomenologically mimic the gluon-pair-vacuum interaction vertices, namely the

model. Based on this model, we study glueball production in pseudoscalar quarkonium decays, explicitly

,

, and

processes. Among them

and

are well-known scalars possessing large glue components, while

is a potential candidate for a pseudoscalar glueball. The preliminary calculation results indicate that these processes are marginally accessible in the presently running experiments BES III, BELLE II, and LHCb.
Search for the

molecular state

in the reaction

*
Authors: Zhang Yang , Wang En , Li De-Min , Li Yu-Xiao
Published: August 2020

Based on the prediction of a

molecular state

with isospin

in the coupled channel approach, we suggest the search for this state in the reaction

. By considering the final state interactions of

and

and the contribution from the

resonance, we observed that the

mass distribution shows a peak around 4000 MeV, which might be associated with the

molecular state

. The search for

in the reaction

is critical for understanding the internal structures of exotic hadrons. Our predictions can be tested by the Belle II and LHCb in future studies.
Analysis of survival probability based on superasymmetric reaction systems *
Authors: Li Na-Na , Bao Xiao-Jun
Published: August 2020

The survival probability of an excited compound nucleus was studied using two different approaches of the washing out of shell effects with excitation energy based on a superasymmetric reaction system. The estimated evaporation residue cross sections based on the two different methods are compared with the available experimental data. Both methods are in agreement with the experimental data to a certain extent for some specific reactions and xn emission channels.
Emission time sequence of neutrons and protons as probes of α-clustering structure *
Authors: Huang Bo-Song , Ma Yu-Gang
Published: August 2020

Neutron–proton momentum correlation functions are constructed from a three-body photodisintegration channel, i.e., core+n+p, and used to explore the spatial-time information of the non-clustering Woods–Saxon spherical structure as well as the

-clustering structures of

or

based on an extended quantum molecular dynamics model. The emission time sequence of neutrons and protons is indicated by the ratio of velocity-gated neutron–proton correlation functions, demonstrating its sensitivity to

-clustering structures. This work sheds light on a new probe for

-clustering structures.
Systematic study of odd-mass 151-161Pm and 154,156Pm isotopes using projected shell model *
Authors: Rani Veerta , Verma Preeti , Singh Suram , Rajput Manvi , Bharti Arun , Bhat G. H. , Sheikh J. A.
Published: August 2020

Inspired by the availability of recent experimental as well as theoretical data on the energy levels of odd-mass 151-161Pm and odd-odd 154,156Pm, we applied the theoretical framework of the projected shell model to further understand the nuclear structure of these nuclei. The calculations closely reproduced the experimental data reported for the yrast bands of these isotopes by assuming an axial (prolate) deformation of ~0.3. Other properties along the yrast line, such as transition energies and transition probabilities, have also been discussed. Band diagrams are plotted to understand their intrinsic multi-quasiparticle structure, which turn out to be dominated by 1-quasiparticle bands for the odd-mass Pm isotopes and 2-quasiparticle bands for the doubly-odd Pm isotopes under study. The present study not only confirms the recently reported experimental/theoretical data, but also extends the already available information on the energy levels and adds new information regarding the reduced transition probabilities.
Warm tachyon inflation and swampland criteria *
Authors: Mohammadi Abolhassan , Golanbari Tayeb , Sheikhahmadi Haidar , Sayar Kosar , Akhtari Lila , Rasheed M. A. , Saaidi Khaled
Published: August 2020

In this study, the scenario of a two-component warm tachyon inflation is considered, where the tachyon field plays the role of the inflaton by driving the inflation. During inflation, the tachyon scalar field interacts with the other component of the Universe, which is assumed to be photon gas, i.e., radiation. The interacting term contains a dissipation coefficient, and the study is modeled based on two different and familiar choices of the coefficient that were studied in the literature. By employing the latest observational data, the acceptable ranges for the free parameters of the model are obtained. For any choice within the estimated ranges, there is an acceptable concordance between the theoretical predictions and observations. Although the model is established based on several assumptions, it is crucial to verify their validity for the obtained values of the free parameters of the model. It is found that the model is not self-consistent for all values of the ranges, and for some cases, the assumptions are violated. Therefore, to achieve both self-consistency and agreement with the data, the parameters of the model must be constrained. Subsequently, we consider the recently proposed swampland conjecture, which imposes two conditions on the inflationary models. These criteria rule out some inflationary models; however, warm inflation is among those that successfully satisfy the swampland criteria. We conduct a precise investigation, which indicates that the proposed warm tachyon inflation cannot satisfy the swampland criteria for some cases. In fact, for the first case of the dissipation coefficient, in which, there is dependency only on the scalar field, the model agrees with observational data. However, it is in direct tension with the swampland criteria. Nevertheless, for the second case, wherein the dissipation coefficient has a dependency on both the scalar field and temperature, the model exhibits acceptable agreement with observational data, and suitably satisfies the swampland criteria.
Strong gravitational lensing for photon coupled to Weyl tensor in Kiselev black hole
Authors: Abbas G. , Mahmood Asif , Zubair M.
Published: August 2020

The objective of the present work is to highlight the phenomena of strong gravitational lensing and deflection angle for the photon coupling with the Weyl tensor in a Kiselev black hole. Here, we have extended the prior work of Chen and Jing (S. Chen and J. Jing, JCAP, 10: 002 (2015)) for a Schwarzschild black hole to a Kiselev black hole. For this purpose, the equation of motion for the photons coupled to the Weyl tensor, null geodesic, and equation of photon sphere in a Kiselev black hole spacetime have been formulated. It is found that the equation of motion of the photons depends not only on the coupling between the photons and the Weyl tensor, but also on the polarization direction of the photons. There is a critical value of the coupling parameter, α, for the existence of the marginally circular photon orbit outside the event horizon, which depends on the parameters of the black hole and the polarization direction of the photons. Further, the polarization directions of the coupled photons and the coupling parameter,

; both modify the features of the photon sphere, angle of deflection, and functions

and

owing to the strong gravitational lensing in the Kiselev black hole spacetime. In addition to this, the observable gravitational lensing quantities and the shadows of the Kiselev black hole spacetime are presented in detail.
Fine micro-thermal structures for Reissner-Nordström black hole *
Authors: Xu Zhen-Ming , Wu Bin , Yang Wen-Li
Published: August 2020

We solve the condundrum on whether the molecules of the Reissner-Nordström black hole interact through the Ruppeiner thermodynamic geometry, basing our study on the concept of the black hole molecule proposed in [Phys. Rev. Lett. 115 (2015) 111302] and choosing the appropriate extensive variables. Our results show that the Reissner-Nordström black hole is indeed an interaction system that may be dominated by repulsive interaction. More importantly, with the help of a novel quantity, namely the thermal-charge density, we describe the fine micro-thermal structures of the Reissner-Nordström black hole in detail. Three different phases are presented, namely the free, interactive, and balanced phases. The thermal-charge density plays a role similar to the order parameter, and the back hole undergoes a new phase transition between the free phase and interactive phase. The competition between the free phase and interactive phase exists, which leads to extreme behavior of the temperature of the Reissner-Nordström black hole. For the extreme Reissner-Nordström black hole, the entire system is completely in the interactive phase. More importantly, we provide the thermodynamic micro-mechanism for the formation of the naked singularity of the Reissner-Nordström black hole.
Daily dynamics of thunderstorms in the North Caucasus
Authors: Kazakova S T , Yurchenko N V , Gyatov R A , Bekkiev K M
Published: August 2020

Based on instrumental observations for the period from 2008 to 2019, regional features of the regime of daily thunderstorm activity in the North Caucasus are analyzed. Thunderstorm activity is calculated at different periods of the day. The temporal and spatial changes of thunderstorm activity are analyzed by time of day and by month. Temporary trends in thunderstorm activity are shown. The characteristic of the dominant tendency and diurnal features in long-term changes in the main characteristics of thunderstorm activity is given; the role of various factors determining these changes is estimated.
Towards time-dependent wave packet tunnelling via complex Riccati equations
Authors: Bonilla-Licea M , Schuch D
Published: August 2020

Since the discovery of tunnelling in the early days of quantum mechanics, there has been considerable interest in finding an effective method to determine the transmission of wave packets through a potential barrier. In this work, we combine the transfer matrix method, known from stationary tunnelling problems, with the construction of Gaussian wave packets via superposition of stationary states with the knowledge about the dynamics of generalized Gaussian-shaped coherent states in terms of complex Riccati equations. In the low-energy regime, this leads to an approximate analytical expression for the transmission probability and its dynamics. Extension to more general potential shapes appears straightforward.
Symmetry: the search for order in Science
Authors: Iachello F
Published: August 2020

After an historical introduction of the concept of symmetry in art and science, the many ways in which symmetry is used today in science are briefly reviewed. A new concept, super-symmetry, introduced in the 1970’s is also briefly reviewed, and the only experimental example of supersymmetry in science is presented. The future of symmetry in science is briefly discussed.
Protocol for pulsed antihydrogen production in the AEḡIS apparatus
Authors: Tietje I C , Amsler C , Antonello M , Belov A , Bonomi G , Brusa R S , Caccia M , Camper A , Caravita R , Castelli F , Cheinet P , Comparat D , Consolati G , Demetrio A , Noto L Di , Doser M , Fanì M , Ferragut R , Fesel J , Gerber S , Giammarchi M , Gligorova A , Glöggler L T , Guatieri F , Haider S , Hinterberger A , Kellerbauer A , Khalidova O , Krasnický D , Lagomarsino V , Malbrunot C , Nowak L , Mariazzi S , Matveev V , Müller S R , Nebbia G , Nedelec P , Oberthaler M , Oswald E , Pagano D , Penasa L , Petracek V , Povolo L , Prelz F , Prevedelli M , Rienäcker B , Røhne O M , Rotondi A , Sandaker H , Santoro R , Testera G , Toso V , Wolz T , Yzombard P , Zimmer C , Zurlo N
Published: August 2020

The AEḡIS collaboration’s main goal is to measure the acceleration of antihydrogen (

H
¯

) due to gravity. The experimental scheme is to form a pulsed beam whose vertical deflection is then measured by means of a moiré deflectometer [1]. Creating pulsed

H
¯

is crucial since it allows a velocity measurement of the antiatoms via time of flight (ToF) necessary to deduce the gravitational acceleration ḡ from the vertical deflection Δs. The aim of this article is to outline the experimental protocol leading up to pulsed antihydrogen production in the AEḡIS experiment.
Effects of timing and magnitude of wing stroke-plane tilt on the escape maneuverability of flapping wing
Authors: Zhou Chao , Chen Long , Wu Jianghao
Published: August 2020

Hummingbirds perform a variety of agile maneuvers, and one of them is the escape maneuver, in which the birds can steer away from threats using only 3–4 wingbeats in less than 150 ms. A distinct kinematic feature that enables the escape maneuver is the rapid backward tilt of the wing stroke plane at the beginning of the maneuver. This feature results in a simultaneous nose-up pitching and backward acceleration. In this work, we investigated how the magnitude and timing of the wing stroke-plane tilt (relative to the phase of flapping cycle) affected the generation of backward thrust, lift, and pitching moment and therefore the maneuverability of escape flight. Investigations were performed using experiments on dynamically scaled robotic wings and computational fluid dynamic simulation based on a simplified harmonic wing stroke and rotation kinematics at Re = 1000 and hummingbird wing kinematics at Re ≈ 10 000. Results showed that the wing stroke-plane tilt timing exerted a strong influence on the aerodynamic force generation. Independent of the tilt magnitude, the averaged backward thrust and pitching moment were maximized when the stroke plane tilt occurred near the end of the half strokes (e.g., upstroke and downstroke). Relative to the other timings of stroke-plane tilt, the ‘optimal’ timings led to a maximal backward tilt of the total aerodynamic force during the wing upstroke; hence, the backward thrust and nose-up pitching moment increased. The ‘optimal’ timings found in this work were in good agreement with those identified in the escape maneuvers of four species of hummingbirds. Therefore, hummingbirds may use a similar strategy in the beginning of their escape maneuver.
High repetition rate deposition of boron nitride films using femtosecond pulsed laser
Authors: Melaibari A , Eltaher M A
Published: August 2020

Cubic (c-BN), and hexagonal (h-BN) boron nitride thin films are of interest in many applications and industries because of their unique mechanical, thermal and chemical properties. In this work, we investigate high repetition rate deposition of BN films using femtosecond pulsed laser deposition. Boron nitride (BN) films were deposited on silicon wafers using 800 nm, 100 fs Ti:sapphire femtosecond laser with 2.4 mJ pulse energy and high repetition rate of 1 kHz using a c-BN target. The deposited films were analyzed using transmission electron microscopy (TEM), scanning electron microscope (SEM), and optical profilometer. Nano-indentation tests were performed to measure the hardness of the adhered film. The results indicate the influence of the high repetition rate on the film growth, crystalline arrangement and adhesion. The experimental work is utilized to identify the process parameters that can be used in pulsed laser deposition (PLD) process to grow thick and adherent BN films.
19-element vertical cavity surface emitting laser arrays with inter-vertical cavity surface emitting laser ridge connectors
Authors: Haghighi Nasibeh , Moser Philip , Zorn Martin , Lott James A
Published: August 2020

We achieve record concurrent combinations of bandwidth (18 GHz), optical output power (150 mW), and wall plug efficiency (30%) with a unique arrangement of 19-element, electrically parallel 980 nm vertical cavity surface emitting laser (VCSEL) arrays. We use a new two-dimensional, quasi honeycomb geometry with inter-VCSEL ridge connectors—made nonconducting by selective thermal oxidation—to improve heat dissipation and facilitate a single top surface anode contact. Via on-wafer probing we perform static and dynamic measurements over the wide temperature range of 23 °C to 85 °C and extract, report, and discuss key array figures-of-merit.
Nonsingular decoupled terminal sliding-mode control for a class of fourth-order under-actuated nonlinear systems with unknown external disturbance
Authors: Rajaei Arman , Vahidi-Moghaddam Amin , Eghtesad Mohammad , Necsulescu D S , Yazdi Ehsan Azadi
Published: August 2020

This study is concerned with the design of a nonsingular decoupled terminal sliding mode controller for a class of fourth-order under-actuated uncertain nonlinear systems with unknown external disturbance. For the unmeasured disturbance, a disturbance observer with finite-time convergence of estimation error to zero is proposed. The nonsingular decoupled terminal sliding mode controller is designed by utilizing the output of the proposed disturbance observer. Also, an input saturation constraint and control singularity are considered in the controller design. The finite-time stability and convergence of the disturbance observer are proved for the closed-loop system. In addition, the control of an electrostatically actuated Timoshenko nanobeam subjected to Casimir force is simulated to demonstrate the effectiveness and performance of the proposed control scheme.
Quantifying the influence of graphene film nanostructure on the macroscopic electrical conductivity
Authors: Rizzi Leo , Wijaya Amaliya F , Palanisamy Logeshwaran Vellingirisamy , Schuster Jörg , Köhne Martin , Schulz Stefan E
Published: August 2020

Graphene films have emerged as a promising nanostructured material class to exploit graphene's outstanding nanoscopic properties on the macroscale. Their potential applications include solar cells (Eda et al 2008 Appl. Phys. Lett.
92, 233305; Müllen et al 2008 Nano Lett.
8, 323–7), antennas (Zhang et al 2018 Electronics
7, 285; Song et al 2018 Carbon
130, 164–9), or electromagnetic interference shielding (Zhou et al 2017 Nanoscale
9, 18613–8; Wan et al 2017 Carbon
122, 74–81; Wang et al 2018 Small
14, 1704332), all of which require a high electrical conductivity. While an outstanding electrical conductivity is a key feature of pristine graphene monolayers, the transfer to the macroscale is challenging. Here, we combined theory and experiment to quantify the impact of specific structural graphene film properties. We synthesized graphene films with systematically varied flake sizes, studied their electrical conductivities, and found excellent agreement to simulations with a three-dimensional random resistor network model. In a further percolation-type study, we computed the critical share of non-conductive elements in a graphene film θ
c = 10% where a substantial loss of electrical conductivity occurs. We prepared mixed films from graphene and graphene oxide to validate the threshold experimentally. In combination, experiments and simulations provide a coherent picture of how the graphene film microstructure is related to the macroscopic electrical conductivity (Rizzi et al 2018 ACS Appl. Mater. Interfaces
10 43088–94; Rizzi et al 2019 Comput. Mater. Sci.
161, 364–70). Our findings provide valuable insights for the production of highly conductive graphene-based macro-materials.
GABA and glutamate deficits from frontotemporal lobar degeneration are associated with disinhibition
Authors: Murley Alexander G , Rouse Matthew A , Jones P Simon , Ye Rong , Hezemans Frank H , O’Callaghan Claire , Frangou Polytimi , Kourtzi Zoe , Rua Catarina , Carpenter T Adrian , Rodgers Christopher T , Rowe James B
Published: August 2020

Behavioural disinhibition is a common feature of the syndromes associated with frontotemporal lobar degeneration (FTLD). It is associated with high morbidity and lacks proven symptomatic treatments. A potential therapeutic strategy is to correct the neurotransmitter deficits associated with FTLD, thereby improving behaviour. Reductions in the neurotransmitters glutamate and GABA correlate with impulsive behaviour in several neuropsychiatric diseases and there is post-mortem evidence of their deficit in FTLD. Here, we tested the hypothesis that prefrontal glutamate and GABA levels are reduced by FTLD in vivo, and that their deficit is associated with impaired response inhibition. Thirty-three participants with a syndrome associated with FTLD (15 patients with behavioural variant frontotemporal dementia and 18 with progressive supranuclear palsy, including both Richardson’s syndrome and progressive supranuclear palsy-frontal subtypes) and 20 healthy control subjects were included. Participants undertook ultra-high field (7 T) magnetic resonance spectroscopy and a stop-signal task of response inhibition. We measured glutamate and GABA levels using semi-LASER magnetic resonance spectroscopy in the right inferior frontal gyrus, because of its strong association with response inhibition, and in the primary visual cortex, as a control region. The stop-signal reaction time was calculated using an ex-Gaussian Bayesian model. Participants with frontotemporal dementia and progressive supranuclear palsy had impaired response inhibition, with longer stop-signal reaction times compared with controls. GABA concentration was reduced in patients versus controls in the right inferior frontal gyrus, but not the occipital lobe. There was no group-wise difference in partial volume corrected glutamate concentration between patients and controls. Both GABA and glutamate concentrations in the inferior frontal gyrus correlated inversely with stop-signal reaction time, indicating greater impulsivity in proportion to the loss of each neurotransmitter. We conclude that the glutamatergic and GABAergic deficits in the frontal lobe are potential targets for symptomatic drug treatment of frontotemporal dementia and progressive supranuclear palsy.
Human model of IRX5 mutations reveals key role for this transcription factor in ventricular conduction
Authors: Al Sayed Zeina R , Canac Robin , Cimarosti Bastien , Bonnard Carine , Gourraud Jean-Baptiste , Hamamy Hanan , Kayserili Hulya , Girardeau Aurore , Jouni Mariam , Jacob Nicolas , Gaignerie Anne , Chariau Caroline , David Laurent , Forest Virginie , Marionneau Céline , Charpentier Flavien , Loussouarn Gildas , Lamirault Guillaume , Reversade Bruno , Zibara Kazem , Lemarchand Patricia , Gaborit Nathalie
Published: August 2020

Aims

Several inherited arrhythmic diseases have been linked to single gene mutations in cardiac ion channels and interacting proteins. However, the mechanisms underlying most arrhythmias, are thought to involve altered regulation of the expression of multiple effectors. In this study, we aimed to examine the role of a transcription factor (TF) belonging to the Iroquois homeobox family, IRX5, in cardiac electrical function.

Methods and results

Using human cardiac tissues, transcriptomic correlative analyses between IRX5 and genes involved in cardiac electrical activity showed that in human ventricular compartment, IRX5 expression strongly correlated to the expression of major actors of cardiac conduction, including the sodium channel, Nav1.5, and Connexin 40 (Cx40). We then generated human-induced pluripotent stem cells (hiPSCs) derived from two Hamamy syndrome-affected patients carrying distinct homozygous loss-of-function mutations in IRX5 gene. Cardiomyocytes derived from these hiPSCs showed impaired cardiac gene expression programme, including misregulation in the control of Nav1.5 and Cx40 expression. In accordance with the prolonged QRS interval observed in Hamamy syndrome patients, a slower ventricular action potential depolarization due to sodium current reduction was observed on electrophysiological analyses performed on patient-derived cardiomyocytes, confirming the functional role of IRX5 in electrical conduction. Finally, a cardiac TF complex was newly identified, composed by IRX5 and GATA4, in which IRX5 potentiated GATA4-induction of SCN5A expression.

Conclusion

Altogether, this work unveils a key role for IRX5 in the regulation of human ventricular depolarization and cardiac electrical conduction, providing therefore new insights into our understanding of cardiac diseases.
Combined Genome and Transcriptome Analyses of the Ciliate Schmidingerella arcuata (Spirotrichea) Reveal Patterns of DNA Elimination, Scrambling, and Inversion
Authors: Smith Susan A , Maurer-Alcalá Xyrus X , Yan Ying , Katz Laura A , Santoferrara Luciana F , McManus George B
Published: August 2020

Schmidingerella arcuata is an ecologically important tintinnid ciliate that has long served as a model species in plankton trophic ecology. We present a partial micronuclear genome and macronuclear transcriptome resource for S. arcuata, acquired using single-cell techniques, and we report on pilot analyses including functional annotation and genome architecture. Our analysis shows major fragmentation, elimination, and scrambling in the micronuclear genome of S. arcuata. This work introduces a new nonmodel genome resource for the study of ciliate ecology and genomic biology and provides a detailed functional counterpart to ecological research on S. arcuata.
Life Course Socioeconomic Disadvantage and the Aging Immune System: Findings From the Health and Retirement Study
Authors: Noppert Grace A , Stebbins Rebecca C , Dowd Jennifer B , Hummer Robert A , Aiello Allison E
Published: August 2020

Objectives

Previous research has documented a consistent association between current socioeconomic status (SES) and cytomegalovirus (CMV). Early life is likely a critical period for CMV exposure and immune development, but less is known about early-life socioeconomic factors and CMV, particularly in older age populations. Using data from the Health and Retirement Study, we investigated the association between life course socioeconomic disadvantage and immune response to CMV among older adults.

Methods

Using ordered logit models, we estimated associations between several measures of socioeconomic disadvantage and the odds of being in a higher CMV Immunoglobulin G (IgG) response category in a sample of 8,168 respondents aged older than 50 years.

Results

We found a significant association between educational attainment and CMV IgG response. Those with less than a high school education had 2.00 (95% confidence interval [CI]: 1.67–2.40) times the odds of being in a higher CMV category compared to those with a college degree or greater. In addition, we also observed a significant association with parental education and CMV response. Individuals with parents having 8 years or less of schooling had 2.32 (95% CI: 2.00–2.70) times the odds of higher CMV response compared to those whose parents had greater than high school education.

Discussion

CMV IgG levels in older adults are associated with both early-life and adult SES. Life course socioeconomic disadvantage may contribute to disparities in immunological aging.
Ageism in Working Life: A Scoping Review on Discursive Approaches
Authors: Previtali Federica , Keskinen Katri , Niska Miira , Nikander Pirjo
Published: August 2020

Background and Objectives

This review investigates the contribution of discursive approaches to the study of ageism in working life. It looks back on the 50 years of research on ageism and the body of research produced by the discursive turn in social science and gerontology.

Research Design and Methods

This study followed the 5-step scoping review protocol to define gaps in the knowledge on ageism in working life from a discursive perspective. About 851 papers were extracted from electronic databases and, according to inclusion and exclusion criteria, 39 papers were included in the final review.

Results

The selected articles were based on discursive approaches and included study participants along the full continuum of working life (workers, retirees, jobseekers, and students in training). Three main themes representing the focal point of research were identified, namely, experiences of ageism, social construction of age and ageism, and strategies to tackle (dilute) ageism.

Discussion and Implications

Discursive research provides undeniable insights into how participants experience ageism in working life, how ageism is constructed, and how workers create context-based strategies to counteract age stereotypes, prejudice, and discrimination. Discursive research on ageism in the working life needs further development about the variety of methods and data, the problematization of age-based labeling and grouping of workers, and a focus on the intersection between age and other social categories. Further research in these areas can deepen our understanding of how age and ageism are constructed and can inform policies about ways of disentangling them in working life.
A phylogenetic view and functional annotation of the animal β1,3-glycosyltransferases of the GT31 CAZy family
Authors: Petit Daniel , Teppa Roxana Elin , Harduin-Lepers Anne
Published: August 2020

The formation of β1,3-linkages on animal glycoconjugates is catalyzed by a subset of β1,3-glycosyltransferases grouped in the Carbohydrate-Active enZYmes family glycosyltransferase-31 (GT31). This family represents an extremely diverse set of β1,3-N-acetylglucosaminyltransferases [B3GNTs and Fringe β1,3-N-acetylglucosaminyltransferases], β1,3-N-acetylgalactosaminyltransferases (B3GALNTs), β1,3-galactosyltransferases [B3GALTs and core 1 β1,3-galactosyltransferases (C1GALTs)], β1,3-glucosyltransferase (B3GLCT) and β1,3-glucuronyl acid transferases (B3GLCATs or CHs). The mammalian enzymes were particularly well studied and shown to use a large variety of sugar donors and acceptor substrates leading to the formation of β1,3-linkages in various glycosylation pathways. In contrast, there are only a few studies related to other metazoan and lower vertebrates GT31 enzymes and the evolutionary relationships of these divergent sequences remain obscure. In this study, we used bioinformatics approaches to identify more than 920 of putative GT31 sequences in Metazoa, Fungi and Choanoflagellata revealing their deep ancestry. Sequence-based analysis shed light on conserved motifs and structural features that are signatures of all the GT31. We leverage pieces of evidence from gene structure, phylogenetic and sequence-based analyses to identify two major subgroups of GT31 named Fringe-related and B3GALT-related and demonstrate the existence of 10 orthologue groups in the Urmetazoa, the hypothetical last common ancestor of all animals. Finally, synteny and paralogy analysis unveiled the existence of 30 subfamilies in vertebrates, among which 5 are new and were named C1GALT2, C1GALT3, B3GALT8, B3GNT10 and B3GNT11. Altogether, these various approaches enabled us to propose the first comprehensive analysis of the metazoan GT31 disentangling their evolutionary relationships.
That’s classified! Inventing a new patent taxonomy
Authors: Billington Stephen D , Hanna Alan J
Published: August 2020

Innovation researchers currently make use of various patent classification schemas, which are hard to replicate. Using machine learning techniques, we construct a transparent, replicable and adaptable patent taxonomy, and a new automated methodology for classifying patents. We contrast our new schema with existing ones using a long-run historical patent dataset. We find quantitative analyses of patent characteristics are sensitive to the choice of classification; our interpretation of regression coefficients is schema dependent. We suggest much of the innovation literature should be carefully interpreted in light of our findings.
Finite difference approach to fourth-order linear boundary-value problems
Authors: Ben-Artzi Matania , Kramer Benjamin
Published: August 2020

Discrete approximations to the equation $$\begin{equation*}L_\textrm{cont}u = u^{(4)} + D(x) u^{(3)} + A(x) u^{(2)} + (A^{\prime}(x)+H(x)) u^{(1)} + B(x) u = f, \quad x\in[0,1]\end{equation*}$$are considered. This is an extension of the Sturm–Liouville case $D(x)\equiv H(x)\equiv 0$ (Ben-Artzi et al. (2018) Discrete fourth-order Sturm–Liouville problems. IMA J. Numer. Anal., 38, 1485–1522) to the non-self-adjoint setting. The ‘natural’ boundary conditions in the Sturm–Liouville case are the values of the function and its derivative. The inclusion of a third-order discrete derivative entails a revision of the underlying discrete functional calculus. This revision forces evaluations of accurate discrete approximations to the boundary values of the second-, third- and fourth-order derivatives. The resulting functional calculus provides the discrete analogs of the fundamental Sobolev properties of compactness and coercivity. It allows us to obtain a general convergence theorem of the discrete approximations to the exact solution. Some representative numerical examples are presented.
The bypassing of healthcare facilities among National Health Insurance Scheme enrollees in Ibadan, Nigeria
Authors: Oladimeji Adetola O , Adewole David A , Adeniji Folashayo
Published: August 2020

Background

Bypassing occurs when patients knowingly visit a health facility other than the one they live nearest to. In Ibadan, southwest Nigeria, the majority of enrollees in the National Health Insurance Scheme (NHIS) receive medical care in just 12% of the available NHIS-accredited facilities. Given that enrollees access healthcare services at highly subsidized rates under the scheme, this study aimed to determine the factors responsible for the observed distribution of enrollees across these health facilities.

Methods

The study was a descriptive cross-sectional survey conducted among NHIS enrollees receiving care at outpatient departments of five randomly selected accredited health facilities in Ibadan. A total of 311 NHIS enrollees were consecutively recruited and a semistructured, pretested, interviewer-administered questionnaire was used to elicit information from respondents. Descriptive and inferential statistics were used to present results at 5% level of significance. Distance traveled by patients from their residence to the facilities was measured using Google maps.

Results

The mean age of respondents was 37.1±16.1 y. There were 167 (53.7%) males and 224 (72.3%) were married. The bypassing rate was 174 (55.3%). More than a third of enrollees, 127 (41.0%), reported that their hospital choice was made based on physician referral, 130 (41.8%) based on personal choice, 26 (8.4%) based upon the recommendation of the Health Management Organization (HMO), while 27 (8.7%) were influenced by friends/family/colleagues. Bypassing was positively associated with educational status (X2 = 13.147, p=0.004). Respondents who bypassed expended additional time and money traveling to the farther away hospitals, 35.1 (±34.66) min and 389.51 (±545.21) naira per visit, respectively.

Conclusion

The level of bypassing among enrollees was fairly high. Enrollees should be properly guided regarding the need to access healthcare in facilities closer to them by their HMOs and physicians in the case of referrals. This will reduce bypassing and the cost of travel leading to better outcomes among enrollees.