bluuebunny/crossref_metadata_2025 huggingface dataset:
Deepening into the nucleation and fission processes of nano-hydrated ammonia clusters - a combined theoretical and experimental study
Authors: Barreiro D , Oostenrijk B , Walsh N , Sankari A , Månsson E P , Maclot S , Sorensen S , Díaz-Tendero S , Gisselbrecht M
Published: June 2020

Synopsis

While largely studied in the macroscopic scale, the dynamics leading to the nucleation and fission of atmospheric aerosols are very poorly understood at the nano or molecular scale. A model system consisting on ionized hydrogen-bonded ammonia and water molecules have been studied experimentally using mass- and 3D momentum spectroscopy and theoretically using ab initio molecular dynamics simulations.
Resonance electron interaction with heterocyclic compounds: vibrational Feshbach resonances and hydrogen atom stripping
Authors: Pshenichnyuk S A , Fabrikant I I , Modelli A , Ptasmska S , Komolov A S
Published: June 2020

Synopsis

We present studies of low-energy resonance electron attachment in a series of 5-membered heterocyclic rings under gas-phase conditions by means of electron transmission spectroscopy and dissociative electron attachment spectroscopy.
Simulation of single cell irradiation by proton beams using TILDA-V
Authors: Alcocer-Ávila M E , Quinto M A , Monti J M , Weck P F , Fojón O A , Rivarola R D , Champion C
Published: June 2020

Synopsis

The purpose of the present work is to emphasize the need for realistic modeling of the biological medium when studying the transport of protons in living matter at the very small scale. In this context, we have used the TILDA-V Monte Carlo track-structure code to simulate the irradiation of single cells with proton beams over the energy range of 10 keV – 100 MeV.
Electron emission induced by Helium ions on water molecule
Authors: Quinto M A , Monti J M , Champion C , Rivarola R D
Published: June 2020

Synopsis

This study focuses on the electron emission induced by He ions on water molecule. In this context, the ionization and the electron capture processes will be investigated using a quantum mechanical description within the continuum distorted wave-eikonal initial state (CDW-EIS) approximation.
Positronium formation in positron-helium collisions in Debye plasma
Authors: Wang Y C , Ma J , Jiao L G , Zhou Y J
Published: June 2020

Synopsis

Positronium formation processes in positron-helium collisions with Debye potentials are studied using the screening approximation model in incident energy range from the threshold to 100 eV for screening parameters μ=0.00-0.25.
Kinematically complete scattering cross sections in collisions between positron and hydrogen atom
Authors: Tőkési K
Published: June 2020

Synopsis

A three-body classical trajectory Monte Carlo (CTMC) method is used to describe positron and hydrogen atom collisions. The total and multi-differential ionization and charge exchange cross sections are calculated and compared with experimental data and other theoretical results.
Calculations of positron scattering, binding and annihilation for atoms and nonpolar molecules with a Gaussian basis
Authors: Swann A R , Gribakin G F
Published: June 2020

Synopsis

Calculations of positron binding, scattering and annihilation using a model correlation potential and a basis of Gaussian states are carried out for a range of atoms and small molecules.
Theoretical analysis of the binding of a positron to acetaldehyde molecule
Authors: Dohi K , Tachikawa M , Kita Y
Published: June 2020

Synopsis

We theoretically analyzed the positron affinity (PA) of acetaldehyde molecule at several vibrational excited states toward the elucidation of physical and chemical origin of H/D isotope shift in the molecular PA value. We found that (i) the acetaldehyde molecule has different PA values and its H/D isotope shift for each vibrational state, and (ii) H/D isotope shift in the PA values at vibrational excited states are mainly due to the change in the dipole moment by the vibrational excitations.
Atomic physics research at HIAF and future perspective
Authors: Ma X , Wen W Q , Zhan S F , Huang Z K , Wang H B , Yang J , Zhu X L , Yu D Y , Cheng R , Mao L J , Yang J C , Sheng L N , Zhou X H , Xu H S , Yuan Y J , Xia J W , Zhao H W , Xiao G Q , Zhan W L
Published: June 2020

Synopsis

A brief introduction to the undergoing HIAF projects in China is given, and the scientific goals as well as the atomic physics programs are discussed. A new science center in the Gulf area near Hongkong will pro-vide unprecedented opportunities for novel scientific researches based on large scale facilities.
Time-dependent effective potential for the ultrafast correlated electron dynamics of molecules in intense laser fields: Application to anisotropic ionization of CO
Authors: Kono H , Ohmura S , Kato T , Ohmura H , Koseki S
Published: June 2020

By using the multiconfiguration time-dependent (TD) Hartree-Fock (MCTDHF) method, we simulated the multielectron dynamics of a CO molecule irradiated by near-IR two-cycle pulses with different carrier envelope phases. The ionization rate calculated is higher when the laser electric field
ε
(t) points from the nucleus C to O than the opposite case, in agreement with the results of two-color ionization experiments. The mechanism of anisotropic tunnel ionization in CO was examined by converting the obtained multielectron dynamics to the representation in terms of TD natural orbitals {ϕj
(t)}. Within the framework of MCTDHF, we derived the unitary equations of motion for {ϕj
(t)}. From the derived equations, we defined the TD effective potentials

{

υ
j

eff

(
t
)

}

that govern the dynamics of {ϕj
(t)}. In

υ

5
σ

eff

(
t
)

for the 5σ HOMO, a narrow hump that originates from two-body electron-electron repulsion is formed on the top of the field-induced distorted barrier near the nucleus C when
ε
(t) points from C to O, which is responsible for the directional anisotropy of tunnel ionization. For 4σ HOMO-2, a high barrier to suppress ionization is formed in

υ

4
σ

eff

(
t
)

when
ε
(t) points from C to O, in correlation with the electron-electron interaction with a 5σ electron on route to ionization. For the opposite phase,

υ

4
σ

eff

(
t
)

becomes barrierless, which enhances high-harmonic generation through ϕ
4σ(t).
Angle-resolved RABBITT : from atoms to molecules
Authors: Joseph J , Holzmeier F , Bresteau D , Spezzani C , Ruchon T , Hergott J F , Tcherbakoff O , D’Oliveira P , Lucchese R R , Houver J C , Carré B , Dowek D
Published: June 2020

Synopsis

We report recent results of photoelectron angular distributions (PADs) for photoionization (PI) of atomic and molecular targets, resolved in the time domain at the attosecond scale, combining electron-ion coincidence momentum spectroscopy and the RABBITT scheme. We propose a unified formalism synthetizing the PAD(θ, τ) results in terms of a reduced set of coefficients.
Semiclassical interference in photoelectron spectra: Holographic structures
Authors: López S D , Arbó D G
Published: June 2020

Synopsis

We theoretically investigate on the holographic structure in doubly differential momentum distribution for atomic photoionization. We use the ab initio solution of the time dependent Schrödinger equantion and the two-step semiclassical model. We see how the holographic structures are formed due to the interference of the direct trajectories of electrons and the rescattered trajectories of electrons. We get rid of intra- and intercycle interferences by removing ionization in the second half of a one-cycle pulse.
Opto-optical modulator (OOM) for extreme ultraviolet pulses
Authors: Olofsson A , Simpson E R , Labeye M , Camp S , Ibrakovic N , Bengtsson S , Schafer K J , Gaarde M B , Mauritsson J
Published: June 2020

Synopsis

There is a profound, almost symbiotic relation between electrons and photons. When light interacts with matter the electrons in the material will start to move and oscillate. When a charged particle, such as an electron, oscillates it will act as a dipole and emit light. We utilize this symbiotic relation and extend the control of light to the extreme ultraviolet (XUV) region using the newly developed XUV opto-optical modulator.
Analytical theory of attosecond transient absorption spectroscopy of perturbatively dressed systems
Authors: Kolbasova D , Santra R
Published: June 2020

Synopsis

The current work provides an elementary explanation of the signals one can obtain in attosecond transient absorption experiments. We perform a perturbative analysis of the transient absorption signal as a function of the time delay between the excitation pulse and the dressing pulse. We discuss an unusual kind of experiment, where the information is gained from the absorption spectrum of an attosecond XUV pump pulse, and the probe pulse gives a reference time, allowing to measure the time evolution of a system. We illustrate our concepts through numerical calculations for a model atom.
High-harmonic generation enhanced by dynamical electron correlation
Authors: Li Y , Sato T , Ishikawa K L
Published: June 2020

Synopsis

We theoretically investigate correlated electron dynamics in high-harmonic generation (HHG), using all-electron ab initio simulations for three-dimensional real alkali-metal atoms. The resulting harmonic spectra exhibit a plateau extended beyond the usual cutoff and a prominent resonance peak, which are clear manifestations of dynamical electron correlation.
Attosecond photoionization dynamics around Ar Cooper minimum
Authors: Lejman M , Alexandridi C , Turconi M , Barreau L , Platzer D , Borot A , Hergott J-F , Tcherbakoff O , Salières P
Published: June 2020

Synopsis

Photoionization time delays between the 3s and 3p subshells of argon have been measured over a large energy range (35-70eV) covering the Cooper minima in both subshells, providing stringent tests for interchannel correlation theories.
Subcycle transfer of photon momentum in nondipole tunneling ionization
Authors: Ni H , Donsa S , Burgdörfer J
Published: June 2020

Synopsis

We study the subcycle transfer of photon momentum in tunneling ionization beyond the dipole approximation using the attoclock setup. We separate the momentum transfer during tunneling and propagation in continuum using the backpropagation method.
Controlling sub-cycle instantaneous optical chirality in the photoionization of chiral molecules
Authors: Rozen S , Comby A , Beauvarlet S , Bloch E , Fabre B , Blanchet V , Descamps D , Petit S , Pons B , Dudovich N , Mairesse Y
Published: June 2020

Synopsis

Photoionization of chiral molecules by circularly polarized light produces characteristic photoelectron angular distributions, showing a strong forward/backward asymmetry with respect to the light propagation axis. Up to now, this process, referred to as Photoelectron Circular Dichroism, has been studied using electric fields with constant ellipticity over the optical period. In this work, we show numerically and experimentally that the chiroptical photoelectron asymmetry can be controlled by engineering the subcycle instantaneous ellipticity and chirality of the ionizing electric field.
Polarization of attosecond pulses generated by two-color laser fields
Authors: Zhu M F , Wang G L , Zhao S F , Li X Y , Zhou X X
Published: June 2020

Synopsis

We propose a circular-elliptical laser field, which consists of a circularly polarized field with its copla-nar counter-rotating elliptical third harmonic pulse, to generate polarized high-order harmonics and attosecond pulses (APs) by He atom. We show that the polarization of APs depends evidently on the ellipticity ξ of harmonic laser field. Most importantly, nearly circular APs can be obtained with a proper ξ. Our results contribute to the generation of high elliptically polarized APs with s-state atom.
Comparison of strong field approximation and quantitative rescattering model in generating of attosecond pulse
Authors: Li X Y , Fan J , Wang X L
Published: June 2020

Synopsis

In this paper, we want to investigate the differences between strong field approximation (SFA) and quantitative rescattering (QRS) model in macroscopically generating attosecond pulse. Our research shows that SFA can give comparable results to that from time-dependent Schrödinger equation (TDSE) in the cut-off range, but it encounters difficulties in reproducing the attosecond pulse of TDSE’s in the low frequency range. However, the results from QRS agree well with that from TDSE method.
Correlation drives a strong attractive force on plasmonic photoelectrons
Authors: Magrakvelidze M , Madjet M E , Chakraborty H S
Published: June 2020

Synopsis

We show that the dynamical electron correlation suppresses the dipole field of incoming photon while inducing a strong attractive force at the spectral region of the giant plasmon resonance of C60. A signature of this force is seen in the form of a binding well in the imaginary part of the induced potential. This attraction can significantly influence the emerging photoelectron’s temporal delay behavior.
Numerical attoclock on atomic and molecular hydrogen
Authors: Serov V , Bray A W , Kheifets A S
Published: June 2020

Synopsis

We simulate attosecond angular streaking on atomic and molecular hydrogen by solving the time-dependent Schrödinger equation (TDSE) driven by a single oscillation circularly polarized laser pulse. We compare results for this simulated “numerical attoclock” with predictions of a semiclassical model based on the saddle point method (SPM). This way we identify the essential physics behind the attoclock measurements. In molecular hydrogen, we observe a strong dependence of the width of the attoclock angular peak on the molecular orientation and attribute it to the two-center electron interference. See Ref. [1] for full detail.
Generation of attosecond pulses in “water window” range by a plasma-based X-ray laser
Authors: Khairulin I R , Antonov V A , Kocharovskaya O
Published: June 2020

Synopsis

We suggest a technique to generate a train of attosecond pulses in “water window” range by hydrogen-like C5+ plasma-based X-ray laser with two sequentical active plasma channels irradiated by two different optical laser fields with orthogonal polarizations. We show also the possibility to transform the radiation of a plasma-based X-ray laser dressed by an optical laser field into a train of attosecond pulses in a resonant absorber irradiated by the different optical field.
Free-free experiments: dressed-atom effects during inelastic electron scattering
Authors: Martin N L S , Kim B N , Weaver C M , Deharak B A
Published: June 2020

Synopsis

Experiments and theory will be presented for the emission/absorption of 1.17 eV photons by electrons during the electron-impact excitation of a helium target in a laser field.
Ag/GaN hybrid nanostructures for optoelectronics applications
Authors: Upadhyaya Kishor , Ayachit Narasimha , Shivaprasad S. M.
Published: June 2020

A hybrid system consisting of Ag nanoparticles dispersed on GaN nanowall network (GaN NWN) exhibits its characteristic optical properties and electronic band structure. XPS studies of this system reveal the presence of a high density of surface charge carriers due to charge transfer between the conduction bands of GaN and Ag. Surface Enhanced Raman Spectrocopy (SERS) studies show that these surface modifications increase the density of hot spots and result in an enhanced Raman signal with an enhancement factor of 107 and limit of detection of 10−10 M. Role of the optoelectronic properties of the substrate on the enhancement of SERS signal has been discussed.
Photocatalytic Hydrogen Production from H2S using Nanostructured CNT blended CdZnS/Fe2O3Thin Film on Glass Substrate
Authors: Raja M. Anthony , Preethi V , Pal Yash , Nalajala Naresh , Gopinath Chinnakonda S
Published: June 2020

A co-precipitation method was employed to prepare the CNT blended CdZnS/Fe2O3photocatalyst. Using the powder photocatalyst, the thin film of CNT blended CdZnS/Fe2O3photocatalyst over a glass substrate was prepared using the drop-casting method. The obtained thin film was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDAX), photoluminescence (PL), and hydrogen production activity studies in order to obtain information on their structural, morphology, chemical composition, optical and hydrogen production efficiency. The hydrogen production activity of catalyst or effective conversion of H2S into hydrogen (H2) and sulfur (S) using thin-film photocatalyst was evaluated using a simulated sulfide solution. The results showed that 1 mg of CNT blended CdZnS/Fe2O3catalyst coated as thin film over glass substrate (4.69 cm2) showed the highest hydrogen production value of 3180 μmol h−1g−1; compared to that of 1 mg CNT blended CdZnS/Fe2O3powder of 2510 μmol h−1g−1. From the above results, it is concluded that the thin film form of photocatlyst produced more hydrogen than the powder form. This is attributed to the effective charge separation and increased specific surface area in thin film photocatalyst.
Effect of lithium fraction fLi on glass transition temperature Tg and ionic conductivity σ of lithium borosilicotitanate glasses
Authors: Satpute N S , Deshpande A V , Raut V D
Published: June 2020

Three different lithium borosilicate glass systems with TiO2 addition have been synthesized by melt quenching technique. The XRD was done for all glass samples to confirm their amorphous nature. Electrical conductivity (σ) of these glasses has been studied by dielectric impedance analyzer as a function of frequency at different temperatures in the range 480 to 650 K. Glass transition temperature Tg for the glasses has been determined by using DTA. The density of all glass samples has been determined. It has been observed that the electrical conductivity increases with increasing content of TiO2 which can be attributed to the modification of the structure by the addition of larger titanium ions. It is observed that higher lithium fraction fLi content glass series has highest conductivity. A good correlation is observed between the ionic conductivity, glass transition temperature and lithium fraction of the glasses. The analysis of IR spectra reveals the presence of Ti ions in tetrahedral TiO4 units as well as creation of NBOs, which supports the conductivity results.
Study of GEM-based detectors spatial resolution
Authors: Kudryavtsev V N , Maltsev T V , Shekhtman L I
Published: June 2020

Gas Electron Multiplier (GEM) based coordinate detectors are used at different high energy physics centres and at Budker Institute of Nuclear Physics particularly. These detectors possess a spatial resolution in ten micron scale together with high rate capability up to 107
cm
−2
s
−1. Thus, the precise investigation of best possible spatial resolution, achieved with GEM-detectors, is the subject of interest. The experimental data, accumulated by the moment, gives the possibility to compare it with the simulation results. The simulation of applied detector configurations includes transport of electrons through the detector and tracking of avalanche evolution inside the working volume, as well as obtaining signal distribution on the readout strips. The spatial resolution, obtained in the simulation of an individual detector, is found to be essentially better (the difference is about two standard deviations) than the experimental results. Further efforts to find out the reasons of the contradiction between the simulation and measurements were made. In particular, the simulation of complete experimental set-up (including tracking detectors) was performed. The results of individual detector simulation and the simulation of complete set-up were determined to generally coincide.
Nanodiamond photocathodes for MPGD-based single photon detectors at future EIC
Authors: Chatterjee C. , Cicala G. , Cicuttin A. , Ciliberti P. , Crespo M.L. , Dalla Torre S. , Dasgupta S. , Gregori M. , Levorato S. , Menon G. , Tessarotto F. , Triloki  , Valentini A. , Velardi L. , Zhao Y. X.
Published: June 2020

The design of a Ring Imaging CHerenkov (RICH) detector for the identification of high momentum particles at the future Electron Ion Collider (EIC) is extremely challenging by using current technology. Compact collider setups impose to construct RICH with short radiator length, hence limiting the number of generated photons. The number of detected photons can be increased by selecting the far UV region. As standard fused-silica windows is opaque below 165 nm, a windowless RICH can be a possible approach. CsI is widely used photocathode (PC) for photon detection in the far UV range. Due to its hygroscopic nature it is very delicate to handle. In addition, its Quantum Effciency (QE) degrades in high intensity ion fluxes. These are the key reasons to quest for novel PC with sensitivity in the far UV region. Recent development of layers of hydrogenated nanodiamond powders as an alternative PC material and their performance, when coupled to the THick Gaseous Electron Multipliers (THGEM)-based detectors, are the objects of an ongoing R&D. We report here some preliminary results on the initial phase of these studies.
Picosecond timing detectors and applications
Authors: Va’vra J
Published: June 2020

Detector examples discussed: MRPCs, MCP-PMTs, Diamond detectors, SiPMTs, Low and high gain Avalanche diodes (LGADs) and Micromegas. We specifically discuss issues such as single pixel vs. multi-pixel tests, small test vs. large physics system results and hidden problems people usually do not want to talk about.
Diamond-Like Carbon for the Fast Timing MPGD
Authors: Colaleo A. , De Robertis G. , Licciulli F. , Maggi M. , Ranieri A. , Simone F. , Valentini A. , Venditti R. , Verwilligen P. , Cesaria M. , Calcagnile L. , Caricato A.P. , Di Giulio M. , Lorusso A. , Manno D. , Martino M. , Perrone A. , Quarta G. , Serra A. , Ressegotti M. , Riccardi C. , Salvini P. , Vitulo P. , Vai I. , Roskas C. , Tytgat M.
Published: June 2020

The present generation of Micro-Pattern Gaseous Detectors (MPGDs) are radiation hard detectors, capable of detecting effciently particle rates of several MHz/cm2, while exhibiting good spatial resolution (≤ 50 µm) and modest time resolution of 5-10 ns, which satisfies the current generation of experiments (High Luminosity LHC upgrades of CMS and ATLAS) but it is not sufficient for bunch crossing identification of fast timing systems at FCC-hh. Thanks to the application of thin resistive films such as Diamond-Like Carbon (DLC) a new detector concept was conceived: Fast Timing MPGD (FTM). In the FTM the drift volume of the detector has been divided in several layers each with their own amplification structure. The use of resistive electrodes makes the entire structure transparent for electrical signals. After some first initial encouraging results, progress has been slowed down due to problems with the wet-etching of DLC-coated polyimide foils. To solve these problems a more in-depth knowledge of the internal stress of the DLC together with the DLC-polyimide adhesion is required. We will report on the production of DLC films produced in Italy with Ion Beam Sputtering and Pulsed Laser Deposition, where we are searching to improve the adhesion of the thin DLC films, combined with a very high uniformity of the resistivity values.
A numerical investigation on the track distortion at the Micromegas based LPTPC endplate
Authors: Bhattacharya D S , Bhattacharya P , Mukhopadhyay S , Majumdar N , Bhattacharya S , Sarkar S , Colas P , Attié D , Ganjour S , Bhattacharya A
Published: June 2020

The R&D activities for the Linear Collider TPC (LCTPC) are currently focused on the adoption of the Micro-Pattern Gaseous Detectors (MPGDs). Different MPGD modules which are commissioned on the endplate of a Large Prototype TPC (LPTPC) at DESY, were tested with a 5 GeV electron beam, under a 1 T magnetic field. During the tests, reduced signal sensitivity as well as distortion in the reconstructed track, were observed at the boundary of these modules.

We have numerically investigated the origin of the track distortions observed close to the edges of the Micromegas modules. The study clearly shows that the electric field non-uniformity near the inter-modular gaps is responsible for such track distortion. We have been able to simulate the observed patterns and magnitudes of distortion successfully. The obtained agreements with 2015 beam test data encourage us to continue with the study and, to propose module design modifications that can alleviate the problem of electrostatic field distortion at the module boundaries.
Ion detector for Accelerator Mass Spectrometry based on low-pressure TPC with THGEM readout
Authors: Bondar A , Buzulutskov A , Frolov E , Parkhomchuk V , Petrozhitskiy A , Shakirova T , Sokolov A
Published: June 2020

A new technique for ion identification in Accelerator Mass Spectrometry (AMS) has been proposed by measuring the ion track ranges using a low-pressure TPC. As a proof of principle, a low-pressure TPC with charge readout using a THGEM multiplier was developed. The tracks of alpha particles from various radioactive sources were successfully recorded in the TPC. The track ranges were measured with a high accuracy, reaching the 2% resolution level. Using these results and the SRIM code simulation, it is shown that the isobaric boron and beryllium ions can be effectively separated at ten sigma level. It is expected that this technique will be applied in the AMS facility in Novosibirsk for dating geological objects, in particular for the geochronology of Cenozoic Era.
Small-pad Resistive Micromegas: Comparison of patterned embedded resistors and DLC based spark protection systems.
Authors: Iodice M. , Alviggi M. , Camerlingo M.T. , Canale V. , Della Pietra M. , Di Donato C. , Iengo P. , Petrucci F. , Sekhniaidze G.
Published: June 2020

We present the development of resistive Micromegas aiming at operation under high rates, up to tens MHz/cm2, focusing on the optimisation of the spark protection resistive layer and the miniaturisation of the readout elements. Several Micromegas detectors have been built with an anode plane matrix of 48x16 rectangular readout pads, each pad 0.8x2.8 mm2. The detectors differ for the spark protection resistive schemes being realised with the following techniques: a pad-patterned embedded resistor by screen printing, and uniform DLC (Diamond Like Carbon structure) layers.

Characterisation and performance studies of the detectors have been carried out by means of radioactive sources, X-Rays, and test beam. A comparison of the performance obtained with the different resistive layouts is presented, in particular focusing on the response under high irradiation and high rate exposure.
Study of Charge-Up Processes in Gas Electron Multipliers
Authors: Hauer P , Urban S , Flöthner K , Ball M , Ketzer B
Published: June 2020

GEM foils are known to collect charged particles on the polyimide part in its holes during the amplification process. This is accompanied by a change of the effective gain. The effect is commonly known as the “charge-up effect”.

In order to study this effect, two complementary approaches were chosen. On the one hand, the effect is studied in an iterative simulation that is based on a finite element calculation of the electrostatic environment and Garfield++ which microscopically tracks charged particles. On the other hand, a dedicated test-detector was setup with a single GEM as an amplification stage. In this study, a special focus lies on the different GEM geometries, i.e. the difference between double-conical and single-conical GEMs.

A quantitative comparison between simulated and measured values will be given. It can be concluded that the typical time-constant of the gain increase is in the order of 1 × 106 initial electrons per hole. For the specific case of a single-conical GEM, it can be shown that the orientation (tapered side pointing upwards or downwards) determines whether the gain increases or decreases.
Test Beam Results and Performance Studies of ATLAS Micromegas Production Modules
Authors: Scholer Patrick
Published: June 2020

The LHC at CERN plans to have a series of upgrades to increase its instantaneous luminosity up to 7.5 × 1034 cm−2·s−1. The ATLAS experiment will upgrade its inner end-cap muon chambers to cope with the increased collision rate expected from the High-Luminosity-LHC. This project, called New Small Wheel, includes resistive Micromegas chambers together with small-strip Thin Gap Chambers, forming a system of ˜2.4 million readout channels in total. This is the first time that Micromegas detectors are built in such a large scale. In total, 128 Micromegas modules up to 3 m2 in size, will be produced in different sites spread across Europe, targetting for an installation at the end of the Long Shutdown 2 of the LHC. One of the first series modules, equipped with a prototype of the final front-end electronics based on the VMM chip, was tested in a muon/pion beam at the H8 beam line of SPS at CERN during the summer of 2018. We present the test setup and performance results, namely effciency and resolution, for perpendicular and inclined tracks. These studies were focused on determining the high voltage working point of the ATLAS Micromegas detectors. Studies with several gas mixtures were also carried out and will be presented.
Multifunctional slot antennas
Authors: Buyanov Yu I , Shipilov S E , Balzovsky E V
Published: June 2020

A variant of a broadband antenna is proposed, which can combine up to four antennas with different polarizations and operating frequencies in one design. The antenna is formed in the shape of an annular slot (annular magnetic current) excited at four points through a quarter of the slot perimeter. The characteristics of directivity and VSWR obtained as a result of numerical simulation using the 4NEC2 software product are presented.
Investigation of the influence of the electromagnetic interaction between volume bodies on the scattering field characteristics
Authors: Dmitrenko A G
Published: June 2020

Using the method of discrete sources, we solve the problem of scattering of an electromagnetic wave by a structure composed of two closely adjacent perfectly conducting triaxial ellipsoids. The solution was realized as a computer code. Using this code, we investigated the influence of the electromagnetic interaction of ellipsoids located at different distances on the scattering field characteristics. Some numerical results are presented.
Types of overvoltages in 10-35 kV distribution networks and modern methods and means of their limitation
Authors: Rybakov L M , Lastochkin S V , Kanjugin O I
Published: June 2020

The basis for the transmission of electrical energy from sources to receivers are overhead power lines 10-35 kV. In these networks, an isolated transmission line or transmission line, grounded through resistors or using arc-quenching reactors, is used. The Republic of Mari El uses networks with isolated transmission line, the total length of which is more than 7000 km. When operating distribution networks, their insulation is affected by a number of internal factors such as long-term operating voltage and voltage fluctuations, short-term overvoltages associated with arc closures, wire breaks, and insulation overlaps. These networks are located on an open area, so they are exposed to lightning overvoltages, temperature, wind loads (mechanical forces), precipitation (snow, humidity). Overvoltages occurring in electrical systems are one of the main factors that significantly affect the reliability of power supply. Despite the short-term effects, overvoltages are characterized by a high multiplicity with respect to the long-term operating voltage, the impact on all electrically connected elements of the system, regardless of the place of occurrence. Overvoltage is the main cause of defects and accelerated aging of structural components. Currently, 90 % of 10-35 kV overhead lines are made on the basis of the use of reinforced concrete structures of supports that require grounding devices, depending on the value of the soil resistivity. Highspeed vacuum circuit breakers are used as switching devices in modern distribution networks of 10-35 kV. The specific properties of vacuum as an arc-quenching medium contribute to the transients in their switching, which require scientific understanding.
Small-signal and noise GaAs pHEMT modeling for low noise amplifier design
Authors: Popov A A , Bilevich D V , Metel A A , Salnikov A S , Dobush I M , Goryainov A E , Kalentyev A A
Published: June 2020

Small-signal and noise GaAs pHEMT modeling techniques that include analytical extraction followed by optimization are demonstrated. The following measurement processing steps were carried out before the parameter extraction: de-embedding, data smoothing and selecting the bias mode appropriate for the extraction of parasitic resistances and inductances. A low-noise amplifier operating in 5G frequency band was designed using the resulting model. A comparison between simulation and measurements of noise factor and S-parameters of the obtained low-noise amplifier is presented.
Automatic device for testing thermal resistance with thermoelectric effect
Authors: Vasiliev I M , Soldatov A I , Dementiev A A , Soldatov A A , Abouellail A
Published: June 2020

This paper presents the results of the developed device for testing thermal resistance of thermointerface. Experiments to determine thermal resistance in different cases of thermal interface application were carried out. Dependence of thermoEMF value is obtained, which occurs between semiconductor element body and cooling system radiator at different quality of thermal interface application.
An ultra-wideband printed dipole antenna of the frequency range from 1 to 3 GHz with wide-angle scanning in the E-plane and low level of cross polarization
Authors: Gevorkyan A V
Published: June 2020

The paper presents the design of the developed ultra-wideband printed dipole antenna. The frequency characteristics of the antennas for different values of the scanning angle in the E-plane are given. When scanning in the angle sector ±50° the operating frequency band of the antenna is in the frequency range from 1 to 3 GHz at the level of the VSWR less than 3. The realized gain is up to 1.5 dB and the antenna efficiency is more than 77%. The cross polarization of the realized gain at all values of the scanning angle is less than minus 27.5 dB.
g-tensor resonance in double quantum dots with site-dependent g-tensors
Authors: Mutter Philipp M , Burkard Guido
Published: June 2020

Pauli spin blockade (PSB) has long been an important tool for spin read-out in double quantum dot (DQD) systems with interdot tunneling t. In this paper we show that the blockade is lifted if the two dots experience distinct effective magnetic fields caused by site-dependent g-tensors g
L and g
R for the left and right dot, and that this effect can be more pronounced than the leakage current due to the spin–orbit interaction (SOI) via spin-flip tunneling and the hyperfine interaction (HFI) of the electron spin with the host nuclear spins. Using analytical results obtained in special parameter regimes, we show that information about both the out-of-plane and in-plane g-factors of the dots can be inferred from characteristic features of the magneto-transport curve. For a symmetric DQD, we predict a pronounced maximum in the leakage current at the characteristic out-of-plane magnetic field

B

*

=
t
/

μ

B

g

z

L

g

z

R

which we term the g-tensor resonance of the system. Moreover, we extend the results to contain the effects of strong SOI and argue that in this more general case the leakage current carries information about the g-tensor components and SOI of the system.
Cell-type-specific mechanical response and myosin dynamics during retinal lens development in Drosophila
Authors: Blackie Laura , Walther Rhian F. , Staddon Michael F. , Banerjee Shiladitya , Pichaud Franck
Published: June 2020

We describe and study the role of the contractile Myosin cytoskeleton in the different epithelial cell types that make up the fly retina. We find that medial contractile Myosin meshworks control the apical geometry and area of retinal cells. Our work also suggests that force transmission within a group of cells depends on cell stiffness.
β-catenin-mediated Wnt signal transduction proceeds through an endocytosis-independent mechanism
Authors: Rim Ellen Youngsoo , Kinney Leigh Katherine , Nusse Roeland
Published: June 2020

A novel tool for quantitative, real-time assessment of Wnt pathway activation was combined with genetic disruption of endocytosis to determine whether receptor endocytosis is required for Wnt signal transduction. Our results in multiple cell lines support that clathrin- or caveolin-mediated endocytosis is dispensable for Wnt signal transduction.
Moving more, ageing happy: findings from six low- and middle-income countries
Authors: Felez-Nobrega Mireia , Haro Josep Maria , Stubbs Brendon , Smith Lee , Koyanagi Ai
Published: June 2020

Background

low levels of well-being (including happiness) in the older population are major global concern given rapid population ageing especially in low- and middle-income countries (LMICs). Physical activity may increase levels of happiness, but data on the older population are scarce, while there are no data from LMICs.

Objective

we investigated the relationship between physical activity and happiness, and the influential factors in this association among older adults employing nationally representative datasets from six LMICs.

Methods

community-based cross-sectional data from the Global Ageing and Adult Health study were analysed. Physical activity was assessed with the Global Physical Activity Questionnaire. Participants were grouped into those who do and do not meet physical activity recommendations. Happiness was assessed with a cross-culturally validated single-item question (range 0–4) with higher scores indicating higher levels of happiness. Multivariable ordinal logistic regression and mediation analyses were performed.

Results

the sample included 14,585 adults aged ≥65 years (mean age = 72.6 ± SD 11.4 years; 55% female). After adjusting for multiple confounders, meeting physical activity guidelines was positively associated with more happiness (fully adjusted model, odds ratio = 1.27; 95% confidence interval = 1.04–1.54). The physical activity–happiness association was largely explained by difficulties in mobility, cognitive impairment, disability and social cohesion, which explained ≥20% of the association.

Conclusions

meeting recommended physical activity levels was positively linked with happiness in older adults from LMICs. Longitudinal and interventional studies among older people in LMICs are warranted to assess directionality and the potential for physical activity promotion to improve mental well-being in this population.
Factors Associated With Physician Recommendation of Home Blood Pressure Monitoring and Blood Pressure in the US Population
Authors: Tang Olive , Foti Kathryn , Miller Edgar R , Appel Lawrence J , Juraschek Stephen P
Published: June 2020

BACKGROUND

Hypertension guidelines recommend home blood pressure monitoring (HBPM) to help achieve blood pressure (BP) control. We hypothesized that HBPM use with a physician recommendation would be associated with lower BP and greater medication adherence.

METHODS

We used data from 6,320 adults with hypertension in the National Health and Nutrition Examination Survey 2009–2014 to characterize the association of (i) provider recommendation for HBPM and (ii) HBPM use on 2 outcomes: measured BP (linear regression) and medication adherence (logistic regression). Provider recommendation, HBPM use, and medication use were self-reported.

RESULTS

Among adults with hypertension, 30.1% reported a physician recommendation for HBPM, among whom 82.0% reported using HBPM. Among those who did not report a physician recommendation for HBPM, 28.3% used HBPM. Factors associated with a physician recommendation were having health insurance, higher education attainment, hypertension awareness, and having a prescription for antihypertensive medication. Among those who reported receiving a physician recommendation, those who used HBPM had a mean BP that was 3.1/4.5 mm Hg lower than those who did not. Those who reported having a physician recommendation and using HBPM were more likely to report hypertension medication adherence (odds ratio 2.9; 95% confidence interval: 2.0, 4.4).

CONCLUSIONS

HBPM use was associated with lower BP and higher medication adherence. Use of HBPM was higher among those with a physician recommendation. These results support a role for physicians in counseling and partnering with patients on HBPM use for BP management.
CCL20-CCR6 axis directs sperm–oocyte interaction and its dysregulation correlates/associates with male infertility‡
Authors: Duan Yong-Gang , Wehry U P , Buhren B A , Schrumpf H , Oláh P , Bünemann E , Yu C-F , Chen S-J , Müller A , Hirchenhain J , Lierop A , Novak N , Cai Zhi-Ming , Krüssel J S , Schuppe H-C , Haidl G , Gerber P A , Allam J-P , Homey B
Published: June 2020

The interaction of sperm with the oocyte is pivotal during the process of mammalian fertilization. The limited numbers of sperm that reach the fallopian tube as well as anatomic restrictions indicate that human sperm–oocyte encounter is not a matter of chance but a directed process. Chemotaxis is the proposed mechanism for re-orientating sperm toward the source of a chemoattractant and hence to the oocyte. Chemokines represent a superfamily of small (8–11 kDa), cytokine-like proteins that have been shown to mediate chemotaxis and tissue-specific homing of leukocytes through binding to specific chemokine receptors such as CCRs. Here we show that CCR6 is abundantly expressed on human sperms and in human testes. Furthermore, radioligand-binding experiments showed that CCL20 bound human sperm in a specific manner. Conversely, granulosa cells of the oocyte-surrounding cumulus complex as well as human oocytes represent an abundant source of the CCR6-specific ligand CCL20. In human ovaries, CCL20 shows a cycle-dependent expression pattern with peak expression in the preovulatory phase and CCL20 protein induces chemotactic responses of human sperm. Neutralization of CCL20 in ovarian follicular fluid significantly impairs sperm migratory responses. Conversely, analyses in infertile men with inflammatory conditions of the reproductive organs demonstrate a significant increase of CCL20/CCR6 expression in testis and ejaculate. Taken together, findings of the present study suggest that CCR6-CCL20 interaction may represent an important factor in directing sperm–oocyte interaction.
Risk of Anal High-grade Squamous Intraepithelial Lesions Among Renal Transplant Recipients Compared With Immunocompetent Controls
Authors: Larsen Helle K , Hædersdal Merete , Thomsen Louise T , Hertzum-Larsen Rasmus , Lok Trine Thorborg , Bonde Jesper , Sørensen Søren S , Hansen Jesper Melchior , Palefsky Joel M , Kjær Susanne K
Published: June 2020

Background

Renal transplant recipients (RTRs) have increased risk of human papillomavirus (HPV)–related cancers, including anal cancer. We investigated the prevalence of anal high-grade intraepithelial lesions (HSILs) in RTRs compared with immunocompetent controls and risk factors for anal HSIL in RTRs.

Methods

We included 247 RTRs and 248 controls in this cross-sectional study. We obtained anal samples for HPV testing with INNO-LiPA and performed high-resolution anoscopy on all participants. The participants completed a questionnaire on lifestyle and sexual habits. We used logistic regression to estimate odds ratios (ORs) of histologically confirmed anal HSIL in RTRs vs controls and risk factors for anal HSIL in RTRs, stratified by sex and anal high-risk (hr) HPV status, adjusting for age, smoking, lifetime sexual partners, and receptive anal sex.

Results

RTRs had higher anal HSIL prevalence than controls, both among men (6.5% vs 0.8%; adjusted OR [aOR], 11.21 [95% confidence interval {CI}, 1.46–291.17]) and women (15.4% vs 4.0%; aOR, 6.41 [95% CI, 2.14–24.10]). Among those with anal hrHPV, RTRs had higher anal HSIL prevalence than controls (33.8% vs 9.5%; aOR, 6.06 [95% CI, 2.16–20.27]). Having had receptive anal sex (aOR, 6.23 [95% CI, 2.23–19.08]) or genital warts (aOR, 4.21 [95% CI, 1.53–11.48]) were risk factors for anal HSIL in RTRs. All HSIL cases occurred in individuals with anal hrHPV.

Conclusions

RTRs had increased risk of anal HSIL compared with immunocompetent controls, with particularly high prevalence in female RTRs. Receptive anal sex, previous genital warts, and anal hrHPV infection were risk factors for anal HSIL in RTRs. Screening for anal HSIL in RTRs should be considered.

Clinical Trials Registration

NCT03018927.
Risk Factors for RecurrentStaphylococcus aureusBacteremia
Authors: Choi Seong-Ho , Dagher Michael , Ruffin Felicia , Park Lawrence P , Sharma-Kuinkel Batu K , Souli Maria , Morse Alison M , Eichenberger Emily M , Hale Lauren , Kohler Celia , Warren Bobby , Hansen Brenda , Medie Felix Mba , McIntyre Lauren M , Fowler Vance G
Published: June 2020

Background

To understand the clinical, bacterial, and host characteristics associated with recurrent Staphylococcus aureus bacteremia (R-SAB), patients with R-SAB were compared to contemporaneous patients with a single episode of SAB (S-SAB).

Methods

All SAB isolates underwent spa genotyping. All isolates from R-SAB patients underwent pulsed-field gel electrophoresis (PFGE). PFGE-indistinguishable pairs from 40 patients underwent whole genome sequencing (WGS). Acute phase plasma from R-SAB and S-SAB patients was matched 1:1 for age, race, sex, and bacterial genotype, and underwent cytokine quantification using 25-analyte multiplex bead array.

Results

R-SAB occurred in 69 (9.1%) of the 756 study patients. Of the 69 patients, 30 experienced relapse (43.5%) and 39 reinfection (56.5%). Age, race, hemodialysis dependence, presence of foreign body, methicillin-resistant Staphyloccus aureus, and persistent bacteremia were individually associated with likelihood of recurrence. Multivariate risk modeling revealed that black hemodialysis patients were nearly 2 times more likely (odds ratio [OR] = 9.652 [95% confidence interval [CI], 5.402–17.418]) than white hemodialysis patients (OR = 4.53 [95% CI, 1.696–10.879]) to experience R-SAB. WGS confirmed PFGE interpretations in all cases. Median RANTES (regulated on activation, normal T cell expressed and secreted) levels in acute phase plasma from the initial episode of SAB were higher in R-SAB than in matched S-SAB controls (P = .0053, false discovery rate < 0.10).

Conclusion

This study identified several risk factors for R-SAB. The largest risk for R-SAB is among black hemodialysis patients. Higher RANTES levels in R-SAB compared to matched controls warrants further study.