bluuebunny/crossref_metadata_2025 huggingface dataset:
Intra‐pulse modulation radar signal recognition based on CLDN network
Authors: Wei Shunjun , Qu Qizhe , Su Hao , Wang Mou , Shi Jun , Hao Xiaojun
Published: December 2019

Automatic modulation classification of radar signals, which plays a significant role in both civilian and military applications, is researched in this study through a deep learning network. In this study, a novel network combined a shallow convolution neural network (CNN), long short‐term memory (LSTM) network and deep neural network (DNN) is proposed to recognise six types of radar signals with different signal‐to‐noise ratio (SNR) levels from −14 to 20 dB. First, raw signal sequences in the time domain, frequency domain and autocorrelation domain are as input for a shallow CNN. Then the features extracted by CNN will be the input of LSTM network. Finally, DNNs will output the signal modulation types directly. The simulation results demonstrate that the accuracies in autocorrelation domain are all more than 90% at −6 dB and close to 100% when SNR > −2 dB. The recognition performances of the three domains are compared. Compared with other recognition methods, the proposed method has higher average accuracy and better performance under low SNR condition. The measured results show that the proposed method has achieved high accuracies of common four kinds of measured radar signals.
Giant radio galaxies in the LOFAR Two-metre Sky Survey
Authors: Dabhade P. , Röttgering H. J. A. , Bagchi J. , Shimwell T. W. , Hardcastle M. J. , Sankhyayan S. , Morganti R. , Jamrozy M. , Shulevski A. , Duncan K. J.
Published: December 2019

Giant radio galaxies (GRGs) are a subclass of radio galaxies, which have grown to megaparsec scales. GRGs are much rarer than normal-sized radio galaxies (< 0.7 Mpc) and the reason for their gigantic sizes is still debated. Here, we report on the biggest sample of GRGs identified to date. These objects were found in the LOFAR Two-metre Sky Survey first data release images, which cover a 424 deg2 region. Of the 239 GRGs found, 225 are new discoveries. The GRGs in our sample have sizes ranging from 0.7 Mpc to 3.5 Mpc and have redshifts (z) between 0.1 and 2.3. Seven GRGs have sizes above 2 Mpc and one has a size of ∼3.5 Mpc. The sample contains 40 GRGs hosted by spectroscopically confirmed quasars. Here, we present the search techniques employed and the resulting catalogue of the newly discovered large sample of GRGs along with their radio properties. In this paper, we also show for the first time that the spectral index of GRGs is similar to that of normal-sized radio galaxies, indicating that most of the GRG population is not dead or is not similar to a remnant-type radio galaxy. We find that 20 out of 239 GRGs in our sample are located at the centres of clusters and we present our analysis on their cluster environment and radio morphology.
Formation of moon systems around giant planets
Authors: Ronnet T. , Johansen A.
Published: December 2019

The four major satellites of Jupiter, known as the Galilean moons, and Saturn’s most massive satellite, Titan, are believed to have formed in a predominantly gaseous circum-planetary disk during the last stages of formation of their parent planet. Pebbles from the protoplanetary disk are blocked from flowing into the circumplanetary disk by the positive pressure gradient at the outer edge of the planetary gap, so the gas drag assisted capture of planetesimals should be the main contributor to the delivery of solids onto circum-planetary disks. However, a consistent framework for the subsequent accretion of the moons remains to be built. Here, we use numerical integrations to show that most planetesimals that are captured within a circum-planetary disk are strongly ablated due to the frictional heating they experience, thus supplying the disk with small dust grains, whereas only a small fraction “survives” their capture. We then constructed a simple model of a circum-planetary disk supplied by ablation, where the flux of solids through the disk is at equilibrium with the ablation supply rate, and we investigate the formation of moons in such disks. We show that the growth of satellites is mainly driven by accretion of the pebbles that coagulate from the ablated material. The pebble-accreting protosatellites rapidly migrate inward and pile up in resonant chains at the inner edge of the circum-planetary disk. We propose that dynamical instabilities in these resonant chains are at the origin of the different architectures of Jupiter’s and Saturn’s moon systems. The assembly of moon systems through pebble accretion can therefore be seen as a down-scaled manifestation of the same process that forms systems of super-Earths and terrestrial-mass planets around solar-type stars and M-dwarfs.
nEDM experiment at PSI: Data-taking strategy and sensitivity of the dataset
Authors: Abel C. , Ayres N.J. , Ban G. , Bison G. , Bodek K. , Bondar V. , Chanel E. , Chiu P.-J. , Daum M. , Emmenegger S. , Ferraris-Bouchez L. , Flaux P. , Griffith W.C. , Harris P.G. , Hild N. , Kermaidic Y. , Kirch K. , Koss P.A. , Krempel J. , Lauss B. , Lefort T. , Lemiere Y. , Leredde A. , Mohanmurthy P. , Musgrave M. , Naviliat-Cuncic O. , Pais D. , Piegsa F.M. , Pignol G. , Rawlik M. , Rebreyend D. , Ries D. , Roccia S. , Rozpedzik D. , Schmidt-Wellenburg P. , Schnabel A. , Severijns N. , Thorne J. , Virot R. , Voigt J. , Weis A. , Wursten E. , Zejma J. , Zsigmond G.
Published: December 2019

We report on the strategy used to optimize the sensitivity of our search for a neutron electric dipole moment at the Paul Scherrer Institute. Measurements were made upon ultracold neutrons stored within a single chamber at the heart of our apparatus. A mercury cohabiting magnetometer together with an array of cesium magnetometers were used to monitor the magnetic field, which was controlled and shaped by a series of precision field coils. In addition to details of the setup itself, we describe the chosen path to realize an appropriate balance between achieving the highest statistical sensitivity alongside the necessary control on systematic effects. The resulting irreducible sensitivity is better than 1 × 10−26e cm. This contribution summarizes in a single coherent picture the results of the most recent publications of the collaboration.
The neutron electric dipole moment experiment at the Spallation Neutron Source
Authors: Leung K.K.H. , Ahmed M. , Alarcon R. , Aleksandrova A. , Baeßler S. , Barrón-Palos L. , Bartoszek L. , Beck D.H. , Behzadipour M. , Bessuille J. , Blatnik M.A. , Broering M. , Broussard L.J. , Busch M. , Carr R. , Chu P.-H. , Cianciolo V. , Clayton S.M. , Cooper M.D. , Crawford C. , Currie S.A. , Daurer C. , Dipert R. , Dow K. , Dutta D. , Efremenko Y. , Erickson C.B. , Filippone B.W. , Fomin N. , Gao H. , Golub R. , Gould C.R. , Greene G.L. , Haase D.G. , Hasell D. , Hawari A.I. , Hayden M.E. , Holley A.T. , Holt R.J. , Huffman P.R. , Ihloff E. , Ito T.M. , Kelsey J. , Kim Y.J. , Korobkina E. , Korsch W. , Lamoreaux S.K. , Leggett E. , Lipman A. , Liu C.-Y. , Long J. , MacDonald S.W.T. , Makela M. , Matlashov A. , Maxwell J. , McCrea M. , Mendenhall M. , Meyer H.O. , Milner R. , Mueller P. , Nouri N. , O'Shaughnessy C.M. , Osthelder C. , Peng J.-C. , Penttila S. , Phan N.S. , Plaster B. , Ramsey J. , Rao T. , Redwine R.P. , Reid A. , Saftah A. , Seidel G.M. , Silvera I.F. , Slutsky S. , Smith E. , Snow W.M. , Sondheim W. , Sosothikul S. , Stanislaus T.D.S. , Sun X. , Swank C.M. , Tang Z. , Dinani R. Tavakoli , Tsentalovich E. , Vidal C. , Wei W. , White C.R. , Williamson S.E. , Yang L. , Yao W. , Young A.R.
Published: December 2019

Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarized 3He, and superfluid 4He will be exploited to provide a sensitivity to ∼ 10−28 e · cm. Our cryogenic apparatus will deploy two small (3 L) measurement cells with a high density of ultracold neutrons produced and spin analyzed in situ. The electric field strength, precession time, magnetic shielding, and detected UCN number will all be enhanced compared to previous room temperature Ramsey measurements. Our 3He co-magnetometer offers unique control of systematic effects, in particular the Bloch-Siegert induced false EDM. Furthermore, there will be two distinct measurement modes: free precession and dressed spin. This will provide an important self-check of our results. Following five years of “critical component demonstration,” our collaboration transitioned to a “large scale integration” phase in 2018. An overview of our measurement techniques, experimental design, and brief updates are described in these proceedings.
Monte Carlo simulations of a neutron lifetime experiment with a big gravitational trap
Authors: Fomin Alexey , Serebrov Anatolii
Published: December 2019

A Monte Carlo model was developed for our current neutron lifetime experiment using storage of ultracold neutrons (UCN) in a big gravitational trap. The model allows us to calculate neutron trajectories in the given geometry, taking into account gravity, and has been used in simulations that reproduce all stages of the experiment. The simulation was proven able to reproduce the time-dependence of the detected neutron count rates. For investigation of systematic effects, the value of the neutron lifetime resulting from the simulation of the experimental procedure was compared to the value entered as an input parameter. In particular, the systematic uncertainty associated with the method of calculating the effective UCN collision frequency in the trap was found not to exceed 0.1 s. In addition, calculations showed that up to 1% uncoated area of the copper trap has a negligible influence on the neutron lifetime result.
aCORN: Measuring the electron-antineutrino correlation in neutron beta decay
Authors: Wietfeldt F.E. , Byron W.A. , Collett B. , Darius G. , DeAngelis C.R. , Dewey M.S. , Hassan M.T. , Jones G. , Komives A. , Mendenhall M.P. , Nico J.S. , Stephenson E.J.
Published: December 2019

The aCORN experiment uses a novel asymmetry method to measure the electron-antineutrino correlation (a-coefficient) in free neutron decay that does not require precision proton spectroscopy. aCORN completed two physics runs at the NIST Center for Neutron Research. The first run on the NG-6 beam line obtained the result a = 0.1090 +/- 0.0030 (stat) +/- 0.0028 (sys), the most precise to date. The second run on the new NG-C high flux beam line promises an improvement in precision to ¡ 2%. In addition we show that an improved measurement of the neutrino asymmetry (B-coefficient) can be made using the aCORN apparatus on a highly polarized neutron beam.
Overview of neutron interferometry at NIST
Authors: Huber Michael G. , Hoogerheide Shannon F. , Arif Muhammad , Haun Robert W. , Wietfeldt Fred E. , Black Timothy C. , Shahi Chandra B. , Heacock Benjamin , Young Albert R. , Taminiau Ivar A.J. , Sarenac Dusan , Cory David G. , Pushin Dmitry A.
Published: December 2019

Neutron interferometry at the National Institute of Standards and Technology is a well-established program that performs experiments in a wide range of areas including materials science, quantum information, precision measurements of coherent and incoherent scattering lengths, and dark energy/fifth force searches. Central to the continued success of this program is the further understanding and elimination of instabilities and coherence-losses whether they are from thermal, vibrational, or dynamical sources. We have spent considerable effort in fabricating new interferometer crystals which have higher maximum fringe visibilities and that can be tailored to specific experiments. We describe the current facilities and a new post-machining fabrication process of crystal annealing.
Measurement of the angular distribution of γ-rays emitted from the compound state after neutron capture by 81Br for a search of T-violation
Authors: Endo Shunsuke , Shimizu Hirohiko M. , Kitaguchi Masaaki , Katsuya Hirota , Yamamoto Tomoki , Ishizaki Kohei , Sato Takumi , Yoshioka Tamaki , Takada Shusuke , Koga Jun , Okudaira Takuya , Sakai Kenji , Kimura Atsushi , Haddock Christopher C.
Published: December 2019

It is known that parity violation can be enhanced in compound nuclei due to mixing of s- and p-waves, and it is suggested that time reversal invariance (T) violation is enhanced by the same mechanism. We are planing a T-violation search using compound nuclei produced in neutron capture reactions. Although 81Br is one of the candidate target nuclei, its sensitivity to T-violation has not yet been determined. For an estimate of the latter, a measurement of the angular distribution of γ-rays emitted in the 81Br(n,γ) reaction was carried out in November 2017, of which we report first results.
ANNI – A pulsed cold neutron beam facility for particle physics at the ESS
Authors: Soldner Torsten , Abele Hartmut , Konrad Gertrud , Märkisch Bastian , Piegsa Florian M. , Schmidt Ulrich , Theroine Camille , Sánchez Pablo Torres
Published: December 2019

Pulsed beams have tremendous advantages for precision experiments with cold neutrons. In order to minimise and measure systematic effects, they are used at continuous sources in spite of the related substantial decrease in intensity. At the European Spallation Source ESS these experiments will profit from the pulse structure of the source and its 50 times higher peak brightness compared to the most intense reactor facilities, making novel concepts feasible. Therefore, the cold neutron beam facility for particle physics ANNI was proposed as part of the ESS instrument suite. The proposed design has been re-optimised to take into account the present ESS cold moderator layout. We present design considerations, the optimised instrument parameters and performance, and expected gain factors for several reference experiments.
Effect of Matrix Content on Mechanical and Thermal Properties of High Graphene Content Composites
Authors: Cilento F. , Martone A. , Cristiano F. , Fina A. , Giordano M.
Published: December 2019

Recently, biomimetic brick and mortar composites (B/M) are gathering great attention due to their outstanding properties. The use of graphene as bricks is expected to achieve good mechanical performances combined with remarkable thermal diffusivity making them optimal candidates for heat spread applications. Macroscopic composites (1 mm thick) have been manufactured at different filler content (up to 100% vol%) and their morphology have been investigated by scanning electron microscopy. Bending test have been carried out on samples for measuring the effect of the polymer amount on the composite. The thermal diffusivity has been investigated, both in plane and cross plane, by light flash analysis (LFA). Coupons showed a well aligned inner structure at each resin content, however the effective performances depends on the capability of stress transfer.
Mortars Containing Sustainable PCM’s for the Energy Efficiency of Buildings
Authors: Frigione Mariaenrica , Lettieri Mariateresa , Sarcinella Antonella , de Aguiar José Luìs Barroso
Published: December 2019

Energy use in buildings represents more than one-third of global energy consumption and contributes to nearly one-quarter of greenhouse gases emission worldwide. The thermal comfort demand represents one of the main cause of the increased energy consumption. To guarantee a thermal indoor comfort, contributing at the same time to the energy saving, the Thermal Energy Storage (TES) methodologies have recently gained interest. These technologies involve the use of a smart material, i.e. a Phase Change Material (PCM), with the capability to absorb/release energy from/in the environment; it can be easily integrated into a building material, such as a mortar. In this work, aerial lime-based mortar with the incorporation of an eco-sustainable PCM have been analyzed with the purpose to improve the energy efficiency of buildings. For its non-toxic nature, a thermoplastic polymer has been selected as PCM, i.e. Poly-Ethylene Glycol (PEG 1000). This material was included in an inert support obtained as byproduct of stone extraction from quarry. The final product, i.e. PEG/stone, can be regarded as a composite to be used as mortar aggregate. A preliminary (chemical and physical) characterization of this compound shown that the sustainable aggregates PEG/stone have an appropriate Latent Heat Thermal Energy Storage (LHTES). The addition of these aggregates into a mortar compositions lead to an unsuitable reduction of mechanical properties.
Sustainable Concrete with Rice Husk Ash (RHA) for Marine Structures
Authors: Martinez Urtecho Francisco A. , Oyanguren Gallo Luis J. , Rodriguez Barboza José U. , Cabrera Elsa Carrera
Published: December 2019

In recent years, attention has focused on addressing the environmental problems caused by the use of construction materials, proposing to develop new environmentally friendly concrete; One of the alternatives that has emerged is to replace cement or aggregates with agricultural waste because its treatment is expensive and not very sustainable; This is the case of rice husk ash (RHA), the main agricultural residue resulting from this cereal, which represents an abundant production worldwide. Marine reinforced concrete structures are in constant exposure to the marine environment, so that their structural capacity and useful life are affected by the breakdown of aggregates, which cause a greater amount of free CaO and MgO in concrete mixtures, and the penetration of chloride ions, which destroy the passive layer of steel and produce cracks in the concrete that cause loss of load and structural damage. In this investigation, cylindrical specimens of conventional concrete and sustainable concrete with cement replacement percentages of 5%, 10% and 15% RHA have been developed. The results show that for a 5% RHA replacement, the compressive strength is greater than conventional concrete at an early age; the disintegration of the aggregates decreases, being for the fine of 9.86% and for the coarse aggregate of 4.34%, the penetrability of sulfate ions decreases as the percentage of RHA replacement increases, the permeability of conventional concrete is much greater with respect to RHA replacement concrete and, finally, the unit cost analysis per cubic meter of RHA concrete is less than conventional concrete
Wear Mechanism of Multilayer AlCrWN/AlCrWSiN-coatings on Cemented Carbide Tools Prepared by Arc Ion Plating in Dry Cutting of Hardened Sintered Steel
Authors: Wada Tadahiro , Hanyu Hiroyuki
Published: December 2019

In this study, to clarify the wear mechanism of the multilayer AlCrWN/AlCrWSiN-coated tool in cutting of hardened sintered steel, the rate of wear in the cutting of hardened sintered steel using three types of coated tools was investigated. The Type I tool had a single layer (Al60, Cr25, W15)N coating film, the Type II tool had a single layer (Al53, Cr23, W14, Si10)N coating film and the Type III tool had a multilayer (Al60, Cr25, W15)N/(Al53, Cr23, W14, Si10)N-coating film. Scanning electron microscope (SEM) observation and electron dispersive X-ray spectrometry (EDS) mapping analysis of the abraded surface of the coating film were performed. The following results were obtained: 1) The wear rate of the Type III tool was the slowest. 2) The area of the worn surface on the rake face “S” and the contact length between the rake face and the chip “D” were measured. Comparing the three types of coated tools, both the “S” and the “D” of Type I tool were the smallest, and those of Type II tool were the largest. 3) The main wear mechanism of Type II and Type III tool showed abrasive wear. However, the main wear mechanism of the Type I tool was both abrasive wear and adhesion wear. 4) The critical scratch load of the Type I tool, 81 N, was lower than that of the Type II or the Type III tool, over 130 N. Therefore, comparing the Type I and Type III tools, due to the wear mechanism of the Type 1 tool being both abrasive wear and adhesion wear, the wear rate of the Type I tool, which has the lower critical scratch load, was slower.
Unusual Causes of Abdominal Pain after Colonoscopy: A Case Series
Authors: Samsami Dorsa , Sargon Peter , Qazi Baseer , Shapiro Alan
Published: December 2019

Colonoscopy is a relatively safe procedure with an overall complication rate between 0.2 and 0.35%. Complications do occur, however, including preparation related complications, colonic perforation, postpolypectomy hemorrhage, postpolypectomy coagulation syndrome, and other less-common miscellaneous complications. Abdominal pain is one of the more common complaints that symptomatic patients will present with after a colonoscopy, occurring up to 5% of the time. Although the cause is usually minor and does not require further workup, gastroenterologists are most concerned about perforation and postpolypectomy coagulation syndrome in the setting of severe abdominal pain. However, as gastroenterologists, we must also be cognizant that there may be other less-common causes of the abdominal pain. The four cases presented here illustrate rare presentations of abdominal pain after colonoscopy, consisting of acute diverticulitis, incarcerated umbilical hernia, acute gangrenous cholecystitis, and rupture of the ovarian cyst.
Oral Sulfate Solution versus Polyethylene Glycol as a Single-Day Preparation for Colonoscopy: A Randomized Control Trial
Authors: Shah Bhavik Bharat , Patel Bubun , Goenka Mahesh Kumar
Published: December 2019

Background Colonoscopy is a principal diagnostic tool for most colonic disorders. Adequate bowel preparation is essential for proper visualization of the mucosa. The aim of this study was to compare the tolerability, efficacy, and safety profile of 1 L of oral sulfate solution (OSS) in comparison to 2 L of polyethylene glycol (PEG) solution.

Methods In this single-center prospective study conducted at our institute, patients were randomly assigned to receive either OSS or PEG solutions for colonoscopy preparation. Patients enrolled in either group completed a questionnaire assessing the taste of the solution used, adverse effects, and number of stools passed. Grading of the bowel cleansing quality was done as per Boston Bowel Preparation (BBP) score.

Results Total of 400 patients, with 222 patients in the PEG group and 178 patients in the OSS group, were assessed. In the PEG group, 148 (66.75%) patients were males and in the OSS group 112 (62.9%) patients were males. There was no statistical significance on comparison of the taste as “good” or “bad” in both groups. All the adverse events were mild to moderate in intensity and their frequencies were comparable for both the groups. The OSS group had better bowel preparation as per the BBP score (p = 0.021) and lesser cecal intubation time (p = 0.028).

Conclusion The present study demonstrated that 1 L of OSS is better than the well-established 2 L PEG solution, in terms of bowel preparation and shorter time to cecal intubation.
Potential for improving the local realization of coordinated universal time with a convolutional neural network
Authors: Tanabe Takehiko , Ye Jiaxing , Suzuyama Tomonari , Kobayashi Takumi , Yamaguchi Yu , Yasuda Masami
Published: December 2019

The time difference between coordinated universal time (UTC) and a hydrogen maser, which is a master oscillator for the local realization of UTC at the National Metrology Institute of Japan (NMIJ), has been predicted by using one of the deep learning techniques called a one-dimensional convolutional neural network (1D-CNN). Regarding the prediction result obtained by the 1D-CNN, we have observed improvement in the accuracy of prediction compared with that obtained by the Kalman filter. Although more investigations are required to conclude that the 1D-CNN can work as a good predictor, the present results suggest that the computational approach based on the deep learning technique may become a versatile method for improving the synchronous accuracy of UTC(NMIJ) relative to UTC.
Enhanced anisotropy and study of magnetization reversal in Co/C60 bilayer thin film
Authors: Mallik Srijani , Sharangi Purbasha , Sahoo Biswajit , Mattauch Stefan , Brückel Thomas , Bedanta Subhankar
Published: December 2019

The interface between the organic semiconductor (OSC)/ferromagnetic (FM) material can exhibit ferromagnetism due to their orbital hybridization. Charge/spin transfer may occur from the FM to OSC layer leading to the formation of “spinterface,” i.e., the interface exhibiting a finite magnetic moment. In this work, the magnetic properties of the Co/C60 bilayer thin film have been studied to probe the interface between the Co and C60 layer. Polarized neutron reflectivity (PNR) measurement indicates that the thickness and moment of the spinterface are ∼2 ± 0.18 nm and 0.8 ± 0.2 μB/cage, respectively. The comparison of the magnetization reversal between the Co/C60 bilayer and the parent single layer Co thin film reveals that spinterface modifies the domain microstructure. Further, the anisotropy of the bilayer system shows a significant enhancement (∼two times) in comparison to its single layer counterpart which is probably due to an additional interfacial anisotropy arising from the orbital hybridization at the Co/C60 interface.
Comparison of methods for the assessment of nonlinearity in short-term heart rate variability under different physiopathological states
Authors: Faes Luca , Gómez-Extremera Manuel , Pernice Riccardo , Carpena Pedro , Nollo Giandomenico , Porta Alberto , Bernaola-Galván Pedro
Published: December 2019

Despite the widespread diffusion of nonlinear methods for heart rate variability (HRV) analysis, the presence and the extent to which nonlinear dynamics contribute to short-term HRV are still controversial. This work aims at testing the hypothesis that different types of nonlinearity can be observed in HRV depending on the method adopted and on the physiopathological state. Two entropy-based measures of time series complexity (normalized complexity index, NCI) and regularity (information storage, IS), and a measure quantifying deviations from linear correlations in a time series (Gaussian linear contrast, GLC), are applied to short HRV recordings obtained in young (Y) and old (O) healthy subjects and in myocardial infarction (MI) patients monitored in the resting supine position and in the upright position reached through head-up tilt. The method of surrogate data is employed to detect the presence and quantify the contribution of nonlinear dynamics to HRV. We find that the three measures differ both in their variations across groups and conditions and in the percentage and strength of nonlinear HRV dynamics. NCI and IS displayed opposite variations, suggesting more complex dynamics in O and MI compared to Y and less complex dynamics during tilt. The strength of nonlinear dynamics is reduced by tilt using all measures in Y, while only GLC detects a significant strengthening of such dynamics in MI. A large percentage of detected nonlinear dynamics is revealed only by the IS measure in the Y group at rest, with a decrease in O and MI and during T, while NCI and GLC detect lower percentages in all groups and conditions. While these results suggest that distinct dynamic structures may lie beneath short-term HRV in different physiological states and pathological conditions, the strong dependence on the measure adopted and on their implementation suggests that physiological interpretations should be provided with caution.
Effect of moisture adsorption on the broadband dielectric response of SiO2-based nanoporous glass
Authors: Komandin Gennadiy A. , Nozdrin Vadim S. , Gavdush Arsenii A. , Pronin Alexei A. , Porodinkov Oleg E. , Spektor Igor E. , Sigaev Vladimir N. , Mikhailov Anton A. , Shakhgildyan Georgii Yu. , Ulitko Vladislav E. , Abdullaev Daniil A.
Published: December 2019

Atmospheric water adsorbed by porous materials may significantly change its electrodynamic response in a wide frequency range. Mechanical and chemical stabilities of silicon dioxide along with a proven manufacturing method of porous SiO2 samples made it convenient for studying the effects of moisture adsorption on various parameters of the porous media. We report the dielectric properties of SiO2-based nanoporous glass in the frequency range of 20 Hz–400 THz at ambient atmospheric conditions and at a low residual pressure of ≤1 mbar. We observed a significant low-frequency dispersion of the complex dielectric permittivity and enhancement of dielectric loss for the porous sample exposed to the ambient moisture. In the terahertz range, the change in dielectric response is smaller and correlates with the moisture saturation of the sample.
Analysis of two avian influenza epidemic models involving fractal-fractional derivatives with power and Mittag-Leffler memories
Authors: Ghanbari Behzad , Gómez-Aguilar J. F.
Published: December 2019

Since certain species of domestic poultry and poultry are the main food source in many countries, the outbreak of avian influenza, such as H7N9, is a serious threat to the health and economy of those countries. This can be considered as the main reason for considering the preventive ways of avian influenza. In recent years, the disease has received worldwide attention, and a large variety of different mathematical models have been designed to investigate the dynamics of the avian influenza epidemic problem. In this paper, two fractional models with logistic growth and with incubation periods were considered using the Liouville-Caputo and the new definition of a nonlocal fractional derivative with the Mittag-Leffler kernel. Local stability of the equilibria of both models has been presented. For the Liouville-Caputo case, we have some special solutions using an iterative scheme via Laplace transform. Moreover, based on the trapezoidal product-integration rule, a novel iterative method is utilized to obtain approximate solutions for these models. In the Atangana-Baleanu-Caputo sense, we studied the uniqueness and existence of the solutions, and their corresponding numerical solutions were obtained using a novel numerical method. The method is based on the trapezoidal product-integration rule. Also, we consider fractal-fractional operators to capture self-similarities for both models. These novel operators predict chaotic behaviors involving the fractal derivative in convolution with power-law and the Mittag-Leffler function. These models were solved numerically via the Adams-Bashforth-Moulton and Adams-Moulton scheme, respectively. We have performed many numerical simulations to illustrate the analytical achievements. Numerical simulations show very high agreement between the acquired and the expected results.
Current channel evolution in ideal Z pinch for general velocity profiles
Authors: Ochs I. E. , Stollberg C. , Kroupp E. , Maron Y. , Fruchtman A. , Kolmes E. J. , Mlodik M. E. , Fisch N. J.
Published: December 2019

Recent diagnostic advances in gas-puff Z pinches at the Weizmann Institute for the first time allow the reconstruction of the current flow as a function of time and radius. These experiments show an unexpected radially outward motion of the current channel, as the plasma moves radially inward [C. Stollberg, “Investigation of a small-scale self-compressing plasma column,” Ph.D. thesis (Weizmann Institute, 2019)]. In this paper, a mechanism that could explain this current evolution is described. We examine the impact of advection on the distribution of current in a cylindrically symmetric plasma. In the case of metric compression, |vr|∝r, the current enclosed between each plasma fluid element and the axis is conserved, and so the current profile maintains its shape. We show that for more general velocity profiles, this simple behavior quickly breaks down, allowing for nonconservation of current in a compressing conductor, rapid redistribution of the current density, and even for the formation of reverse currents. In particular, a specific inward radial velocity profile is shown to result in radially outward motion of the current channel, recovering the surprising current evolution discovered at the Weizmann Institute.
Broadband electron paramagnetic resonance spectrometer from 1 to 15 GHz using metallic coplanar waveguide
Authors: Jing Ke , Lan Ziheng , Shi Zhifu , Mu Shiwei , Qin Xi , Rong Xing , Du Jiangfeng
Published: December 2019

We report a broadband electron paramagnetic resonance (EPR) spectrometer that operates continuously in the frequency range from 1 to 15 GHz. A broadband metallic coplanar waveguide is utilized as the probe. The system is capable of performing EPR measurements in both continuous wave and pulsed modes. Its performance has been tested with a sample, named 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl powder, at room temperature. In the continuous wave mode, the sensitivity of the spectrometer is estimated to be 3.3×1012 spins/gaussHz at 13 GHz. In the pulsed mode, inversion recovery experiments were carried out to obtain the spin-lattice relaxation time of the sample.
On-chip polarization rotator for type I second harmonic generation
Authors: Stanton Eric J. , Chang Lin , Xie Weiqiang , Malik Aditya , Peters Jon , Chiles Jeff , Nader Nima , Navickaite Gabriele , Sacchetto Davide , Zervas Michael , Srinivasan Kartik , Bowers John E. , Papp Scott B. , Nam Sae Woo , Mirin Richard P.
Published: December 2019

We demonstrate a polarization rotator integrated at the output of a GaAs waveguide producing type I second harmonic generation (SHG). Form-birefringent phase matching between the pump fundamental transverse electric (TE) mode near 2.0 µm wavelength and the signal fundamental transverse magnetic (TM) mode efficiently generates light at 1.0 µm wavelength. A SiN waveguide layer is integrated with the SHG device to form a multifunctional photonic integrated circuit. The polarization rotator couples light between the two layers and rotates the polarization from TM to TE or from TE to TM. With a TE-polarized 2.0 µm pump, type I SHG is demonstrated with the signal rotated to TE polarization. Passive transmission near 1.0 µm wavelength shows ∼80% polarization rotation across a broad bandwidth of ∼100 nm. By rotating the signal polarization to match that of the pump, this SHG device demonstrates a critical component of an integrated self-referenced octave-spanning frequency comb. This device is expected to provide crucial functionality as part of a fully integrated optical frequency synthesizer with resolution of less than one part in 1014.
Early-stage corrosion, ion release, and the antibacterial effect of copper and cuprous oxide in physiological buffers: Phosphate-buffered saline vs Na-4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
Authors: Luo Jiaqi , Hein Christina , Pierson Jean-François , Mücklich Frank
Published: December 2019

Copper surfaces are well known for their antibacterial effects due to the release of copper ions. This benefit has been shown in many antibacterial efficiency tests, however, without considering the corrosion behaviors of copper in the physiological solutions, which could play an indispensable role in ion release from the metallic surface. This study compared the ground copper surface and sputtered cuprous oxide (Cu2O) coating in two common physiological buffers: phosphate-buffered saline (PBS) and Na-4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (Na-HEPES). The growth of the cuprous oxide (Cu2O) layer was found on copper in pure PBS, inhibiting further copper ion release. In contrast, a continuous release of copper ions was recorded in Na-HEPES for 3 h, where no oxide formation was observed. The antibacterial efficiency of copper (against E. coli) was measured and discussed with the ion release kinetics in the presence of E. coli. Similar results were obtained from Cu2O coating, ruling out its assisting role in showing the antibacterial property from copper surfaces, but they did indicate the importance of taking environmental parameters into consideration in interpreting the antibacterial efficiency of copper surfaces.
High-detectivity infrared photodetector based on InAs submonolayer quantum dots grown on GaAs(001) with a 2 × 4 surface reconstruction
Authors: Alzeidan A. , Claro M. S. , Quivy A. A.
Published: December 2019

The submonolayer quantum dots of an infrared photodetector were grown by molecular beam epitaxy in the presence of a very low As flux and a 2 × 4 surface reconstruction in order to effectively nucleate small two-dimensional InAs islands that are required to form such nanostructures. A specific detectivity of 9.2 × 1010 cm Hz1/2 W−1 was obtained at 10 K with a bias of 1.0 V.
Distinct dependence on size of Pt and Rh nanoclusters on graphene/Pt(111) in the decomposition of methanol-d4
Authors: Ansari A. S. , Chern Zhao-Ying , Cai Pei-Yang , Huang Yen-Wen , Liao Guan-Jr , Wang Jeng-Han , Luo Meng-Fan
Published: December 2019

Pt and Rh nanoclusters, grown on deposition of Pt and Rh vapors onto graphene/Pt(111), show separate reactivity toward the decomposition of methanol-d4. The Pt (Rh) clusters had a mean diameter 2.0–3.5 nm (2.1–4.0 nm) and height 0.45–0.94 nm (0.41–0.9 nm) evolving with the coverage; they were structurally ordered, having an fcc phase and growing in (111) orientation, and had lattice constants similar to their bulk values. Methanol-d4 on the Pt clusters did not decompose but desorbed mostly, disparate from that on Pt(111) surface; the disparity arose as the adsorption energies of methanol-d4 on most surface sites of the Pt clusters became smaller than their single crystal counterpart. This size effect, nevertheless, did not apply on the Rh clusters, despite their similar atomic stacking; the Rh clusters showed a reactivity similar to that of the Rh(111) surface because the adsorption energies of methanol-d4 on both Rh clusters and Rh(111) are comparable. The distinct size dependence was rationalized through their electronic structures and charge distribution of Fukui function mapping. Our results suggest that reactive transition metals do not necessarily become more reactive while they are scaled down to nanoscale; their reactivity evolves with their size in a manner largely dependent on their electronic nature.
Drastically modulating the structure, fluorescence, and functionality of doxorubicin in lipid membrane by interfacial density control
Authors: Li Jianhui , Chen Shun-Li , Hou Yi , Zhou Jia , Yuan Qunhui , Gan Wei
Published: December 2019

In this work, we report on the observation of a drastic modulation of the fluorescence emission of an anticancer drug, doxorubicin, at the lipid interface during the variation of its molecular density at the interface. The emission efficiency of doxorubicin in the lipid membrane was modulated in the range of less than 10% to above 300% that in the aqueous solution. The corresponding changes in the structure and functionality of doxorubicin on the lipid surface were analyzed with the aid of second harmonic generation and theoretical calculation. It was observed that doxorubicin molecules aggregated on the lipid membrane at a relatively high interfacial density. However, this aggregation may not cause interfacial domain large enough to alter the permeability of the lipid bilayer. At an even higher doxorubicin density, the domain of the aggregated doxorubicin molecules induced a cross-membrane transportation.
Super-resolution reconstruction of turbulent velocity fields using a generative adversarial network-based artificial intelligence framework
Authors: Deng Zhiwen , He Chuangxin , Liu Yingzheng , Kim Kyung Chun
Published: December 2019

A general super-resolution reconstruction strategy was proposed for turbulent velocity fields using a generative adversarial network-based artificial intelligence framework. Two advanced neural networks, i.e., super-resolution generative adversarial network (SRGAN) and enhanced-SRGAN (ESRGAN), were first applied in fluid mechanics to augment the spatial resolution of turbulent flow. As a validation, the flow around a single-cylinder and a more complicated wake flow behind two side-by-side cylinders were experimentally measured using particle image velocimetry. The spatial resolution of the coarse flow field can be successfully augmented by 42 and 82 times with remarkable accuracy. The reconstruction performances of SRGAN and ESRGAN were comprehensively investigated and compared, including an analysis of the recovered instantaneous flow field, statistical flow quantities, and spatial correlations. The results convincingly demonstrated that both models can reconstruct the high-spatial-resolution flow field accurately even in an intricate flow configuration, and ESRGAN can provide a better reconstruction result than SRGAN in the mean and fluctuation flow field.
Geometry control of size selected Pt clusters bound to Si substrate surface by cluster impact deposition
Authors: Fukui Nobuyuki , Yasumatsu Hisato
Published: December 2019

Geometry of platinum clusters, PtN (N = 30–71), supported on a silicon substrate was investigated, aiming to control the geometry. The supported clusters were prepared by the impact of size-selected PtN+ onto the substrate at a given collision energy (cluster-impact deposition), and their geometry was observed by means of a scanning-tunneling microscope. Even at the collision energy of 1 eV per Pt atom, sufficiently strong Pt–Si interaction between PtN (N = 30 and 45) and the Si substrate allows them to be supported as close-packed monatomic-layered Pt disks, while at N = 60, multilayered shapes exist besides the monatomic-layered shape, the fraction of which increases at N = 71. When the collision energy is increased, Si atoms located at the interface between the cluster and Si substrate dissolve into the cluster, and with further increase in the collision energy, the Pt–Si cluster is partially implanted into the substrate. The transition in the shape of the supported clusters with the collision energy and the cluster size was explained according to the deformation of the clusters and the substrate surface by the cluster impact. It is proposed that the momentum of PtN+ per its cross section is a good index to control the geometry in the case of strong cluster-support interaction such as Pt and Si.
Spectral dependencies of terahertz emission from femtosecond laser excited surfaces of germanium crystals
Authors: Norkus R. , Nevinskas I. , Krotkus A.
Published: December 2019

Pulsed terahertz emission excitation spectra from germanium crystals are being presented. The most intense terahertz pulses from germanium crystals are emitted at quanta energies coinciding with technologically significant telecommunication wavelengths. The terahertz generation mechanisms are an interplay of the photocurrent surge in the surface electric field and the photo-Dember effect. Remarkably, the terahertz emission is also observed at quanta energies below the direct bandgap of this material even when photoexcited at a surface normal. This is the result of a broken symmetry of effective electron mass in the L valleys.
A cryogenic single nanoparticle action spectrometer
Authors: Esser Tim K. , Hoffmann Benjamin , Anderson Scott L. , Asmis Knut R.
Published: December 2019

A nanoparticle (NP) mass spectrometer designed to perform action spectroscopy on single NPs at cryogenic temperatures is described. NPs from an electrospray ion source with masses ranging from 460 to 740 MDa are injected and trapped in a temperature controllable (8–350 K) split-ring electrode ion-trap characterized by improved optical access and trapping potential. After excess NPs are ejected from the trap, the mass-to-charge ratio and subsequently the absolute mass of the trapped NP are determined nondestructively using Fourier transformation and resonant excitation methods. The setup allows us to monitor the mass variation of a single NP as a function of the ion-trap temperature, collision-gas pressure, and irradiation laser power. Ion-trap temperature controlled N2 adsorption at cryogenic temperatures onto a single, ∼90 nm diameter SiO2 NP is demonstrated and characterized. We further show that laser irradiation at 532 nm leads to power-dependent changes in the effective N2 adsorption rate of the particle, which can be monitored and ultimately exploited to measure absorption spectra of a single NP.
Solid wall and open boundary conditions in hybrid recursive regularized lattice Boltzmann method for compressible flows
Authors: Feng Y. , Guo S. , Jacob J. , Sagaut P.
Published: December 2019

Complex geometries and open boundaries have been intensively studied in the nearly incompressible lattice Boltzmann method (LBM) framework. Therefore, only few boundary conditions for the high speed fully compressible LBM have been proposed. This paper deals with the definition of efficient boundary conditions for the compressible LBM methods, with the emphasis put on the newly proposed hybrid recursive regularized D3Q19 LBM (HRR-LBM) with applications to compressible aerodynamics. The straightforward simple extrapolation-based far-field boundary conditions, the characteristic boundary conditions, and the absorbing sponge layer approach are extended and estimated in the HRR-LBM for the choice of open boundaries. Moreover, a cut-cell type approach to handle the immersed solid is proposed to model both slip and no-slip wall boundary conditions with either isothermal or adiabatic behavior. The proposed implementations are assessed considering the simulation of (i) isentropic vortex convection with subsonic to supersonic inflow and outflow conditions, (ii) two-dimensional (2D) compressible mixing layer, (iii) steady inviscid transonic flow over a National Advisory Committee for Aeronautics (NACA) 0012 airfoil, (iv) unsteady viscous transonic flow over a NACA 0012 airfoil, and (v) three-dimensional (3D) transonic flows over a German Aerospace Center (DLR) F6 full aircraft configuration.
Weyl nodes and magnetostructural instability in antiperovskite Mn3ZnC
Authors: Teicher S. M. L. , Svenningsson I. K. , Schoop L. M. , Seshadri R.
Published: December 2019

The room temperature ferromagnetic phase of the cubic antiperovskite Mn3ZnC is suggested from first-principles calculation to be a nodal line Weyl semimetal. Features in the electronic structure that are the hallmark of a nodal line Weyl state—a large density of linear band crossings near the Fermi level—can also be interpreted as signatures of a structural and/or magnetic instability. Indeed, it is known that Mn3ZnC undergoes transitions upon cooling from a paramagnetic to a cubic ferromagnetic state under ambient conditions and then further into a noncollinear ferrimagnetic tetragonal phase at a temperature between 250 K and 200 K. The existence of Weyl nodes and their destruction via structural and magnetic ordering are likely to be relevant to a range of magnetostructurally coupled materials.
A hyperspectral microscope based on an ultrastable common-path interferometer
Authors: Candeo A. , Nogueira de Faria B. E. , Erreni M. , Valentini G. , Bassi A. , de Paula A. M. , Cerullo G. , Manzoni C.
Published: December 2019

We introduce a wide field hyperspectral microscope using the Fourier-transform approach. The interferometer is based on the translating-wedge-based identical pulses encoding system, a common-path birefringent interferometer which combines compactness, intrinsic interferometric delay precision, long-term stability, and insensitivity to vibrations. We describe two different implementations of our system, which maximize fringe visibility and phase invariance over the field of view, respectively. We also demonstrate that our system can be installed as an add-on in a commercial microscope. We show high-quality hyperspectral fluorescence microscopy from stained cells and powders of inorganic pigments in the spectral range from 400 to 1100 nm, proving that our device is suited to biology and materials science. We also introduce an acquisition method that synthesizes a tunable spectral filter, providing band-passed images with the measurement of only two maps.