bluuebunny/crossref_metadata_2025 huggingface dataset:
Signal timing parameters inference method at intersections using license plate recognition data
Authors: Lin Qinghai , Chen Jinyong , Li Guilong , He Zhaocheng
Published: May 2022

Signal timing parameters are essential components in traffic signal control (TSC). It affects not only traffic management, but also traffic safety. However, due to the confidential issues of the traffic management department, or lack of data integration from different signal manufacturers, it is intractable to obtain the city‐scale signal timing data. In the previous studies, some existing estimation methods focused on a single parameter and fixed‐timing scheme. To tackle this issue, this study attempts to develop an integrated parameters inference method based on license plate recognition (LPR) data, considering phase weight, average phase duration information and the overall phases of the intersections. In particular, the proposed method includes phase sequence inference model, cycle length inference model and phase duration inference model. To testify the performance of the proposed method, a real‐world LPR dataset from Guangzhou, China, is applied. Numerical results show that the proposed method performs more efficiently on parameter inferences than the state‐of‐the‐art (SOTA) approach. For instance, in the given research time period, the mean absolute error (MAE) of each phase duration is 2 s averagely (6.32 s in the SOTA approach), and the mean relative error (MRE) of cycle length is 0.91% (11.67% in the SOTA approach).
The gravitational field of X-COP galaxy clusters
Authors: Eckert D. , Ettori S. , Pointecouteau E. , van der Burg R. F. J. , Loubser S. I.
Published: May 2022

The mass profiles of massive dark matter halos are highly sensitive to the nature of dark matter and potential modifications of the theory of gravity on large scales. The Λ cold dark matter (CDM) paradigm makes strong predictions on the shape of dark matter halos and on the dependence of the shape parameters on halo mass, such that any deviation from the predicted universal shape would have important implications for the fundamental properties of dark matter. Here we use a set of 12 galaxy clusters with available deep X-ray and Sunyaev–Zel’dovich data to constrain the shape of the gravitational field with an unprecedented level of precision over two decades in radius. We introduce a nonparametric framework to reconstruct the shape of the gravitational field under the assumption of hydrostatic equilibrium and compare the resulting mass profiles to the expectations of Navarro–Frenk–White (NFW) and Einasto parametric mass profiles. On average, we find that the NFW profile provides an excellent description of the recovered mass profiles, with deviations of less than 10% over a wide radial range. However, there appears to be more diversity in the shape of individual profiles than can be captured by the NFW model. The average NFW concentration and its scatter agree very well with the prediction of the ΛCDM framework. For a subset of systems, we disentangle the gravitational field into the contribution of baryonic components (gas, brightest cluster galaxy, and satellite galaxies) and that of dark matter. The stellar content dominates the gravitational field inside ∼0.02R500 but is responsible for only 1–2% of the total gravitational field inside R200. The total baryon fraction reaches the cosmic value at R200 and slightly exceeds it beyond this point, possibly indicating a mild level of nonthermal pressure support (10 − 20%) in cluster outskirts. Finally, the relation between observed and baryonic acceleration exhibits a complex shape that strongly departs from the radial acceleration relation in spiral galaxies, which shows that the aforementioned relation does not hold at the galaxy-cluster scale.
Nearby galaxies in the LOFAR Two-metre Sky Survey
Authors: Heesen V. , Staffehl M. , Basu A. , Beck R. , Stein M. , Tabatabaei F. S. , Hardcastle M. J. , Chyży K. T. , Shimwell T. W. , Adebahr B. , Beswick R. , Bomans D. J. , Botteon A. , Brinks E. , Brüggen M. , Dettmar R.-J. , Drabent A. , de Gasperin F. , Gürkan G. , Heald G. H. , Horellou C. , Nikiel-Wroczynski B. , Paladino R. , Piotrowska J. , Röttgering H. J. A. , Smith D. J. B. , Tasse C.
Published: May 2022

Context. Cosmic rays and magnetic fields are key ingredients in galaxy evolution, regulating both stellar feedback and star formation. Their properties can be studied with low-frequency radio continuum observations that are free from thermal contamination.

Aims. We define a sample of 76 nearby (< 30 Mpc) galaxies with rich ancillary data in the radio continuum and infrared from the CHANG-ES and KINGFISH surveys, which will be observed with the LOFAR Two-metre Sky Survey (LoTSS) at 144 MHz.

Methods. We present maps for 45 of them as part of the LoTSS data release 2 (LoTSS-DR2), where we measure integrated flux densities and study integrated and spatially resolved radio spectral indices. We investigate the radio–star formation rate (SFR) relation using SFRs derived from total infrared and Hα + 24-μm emission.

Results. The radio–SFR relation at 144 MHz is clearly super-linear with L144 MHz ∝ SFR1.4−1.5. The mean integrated radio spectral index between 144 and ≈1400 MHz is ⟨α⟩= − 0.56 ± 0.14, in agreement with the injection spectral index for cosmic ray electrons (CREs). However, the radio spectral index maps show variation of spectral indices with flatter spectra associated with star-forming regions and steeper spectra in galaxy outskirts and, in particular, in extra-planar regions. We found that galaxies with high SFRs have steeper radio spectra; we find similar correlations with galaxy size, mass, and rotation speed.

Conclusions. Galaxies that are larger and more massive are better electron calorimeters, meaning that the CRE lose a higher fraction of their energy within the galaxies. This explains the super-linear radio–SFR relation, with more massive, star-forming galaxies being radio bright. We propose a semi-calorimetric radio–SFR relation that employs the galaxy mass as a proxy for the calorimetric efficiency.
Retrieving cosmological information from small-scale CMB foregrounds
Authors: Gorce Adélie , Douspis Marian , Salvati Laura
Published: May 2022

Recent results of ground-based telescopes, giving high-quality measurements of the cosmic microwave background (CMB) temperature power spectrum on small scales (below 1 deg) motivate the need for an accurate model of foregrounds, which dominate the primary signal at these multipoles. In a previous work, we have shown that cosmological information could be retrieved from the power spectrum of the thermal Sunyaev Zel’dovich (SZ) effect. In this work, we introduce a physically motivated model of the Epoch of Reionisation in the cosmological analysis of CMB data, which is coherent on all scales. In particular, at high multipoles, the power spectrum of the kinetic SZ (kSZ) effect is inferred from a set of cosmological and reionisation parameters by a machine-learning algorithm. First including an asymmetric parameterisation of the reionisation history in thePlanck2018 data analysis, we retrieve a value of the Thomson optical depth consistent with previous results, but stemming from a completely different history of reionisation in which the first luminous sources light up as early asz = 15. Considering the latest small-scale data from the South Pole telescope (SPT) and letting the cosmology free to vary, we find that including the new cosmology-dependent tSZ and kSZ spectra helps tighten the constraints on their amplitudes by breaking their degeneracy. We report a 5σmeasurement of the kSZ signal atℓ = 3000, D3000kSZ= 3.4−0.3+0.5μK2at the 68% confidence level (C.L.), marginalised over cosmology, as well as an upper limit on the patchy signal from reionisation D3000pkSZ< 1.6 μK2(95% C.L.). Additionally, we find that the SPT data favour slightly earlier reionisation scenarios thanPlanck, leading toτ= 0.062−0.015+0.012and a reionisation midpointzre= 7.9−1.3+1.1(68% C.L.), which is in line with constraints from high-redshift quasars and galaxies.
A first look at the submillimeter Sun with ALMA
Authors: Alissandrakis C. E. , Bastian T. S. , Nindos A.
Published: May 2022

We present the first full-disk solar images obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 7 (0.86 mm; 347 GHz). In spite of the low spatial resolution (21″), several interesting results were obtained. During our observation, the sun was practically devoid of active regions. Quiet Sun structures on the disk are similar to those in Atmospheric Imaging Assembly images at 1600 Å and 304 Å, after the latter are smoothed to the ALMA resolution, as noted previously for Band 6 (1.26 mm) and Band 3 (3 mm) images; they are also similar to negative Hα images of equivalent resolution. Polar coronal holes, which are clearly seen in the 304 Å band and small Hα filaments, are not detectable at 0.86 mm. We computed the center-to-limb variation of the brightness temperature, Tb, in Band 7, as well as in Bands 6 and 3, which were obtained during the same campaign, and we combined them to a unique curve of Tb(log μ100), where μ100 is the cosine of the heliocentric angle reduced to 100 GHz. Assuming that the absolute calibration of the Band 3 commissioning observations is accurate, we deduced a brightness temperature at the center of the disk of 6085 K for Band 7, instead of the value of 5500 K, extrapolated from the recommended values for Bands 3 and 6. More importantly, the Tb(log μ100) curve flattens at large values of μ100, and so does the corresponding Te(log τ100) at large τ100. This is probably an indication that we are approaching the temperature minimum.
Ein langwieriger Prozess – Anerkennung von Berufsabschlüssen aus dem Ausland
Authors: Scholz-Schwärzler Nadine
Published: May 2022

Nadine Scholz-Schwärzler ist Dozentin an einer Berufsfachschule für Ergotherapie in Bayern. Dort begleitet sie unter anderem Ergotherapeut*innen, die ihren Berufsabschluss im Ausland absolviert haben und diesen nun in Deutschland anerkennen lassen möchten – ein Prozedere, das einige Hürden birgt.
Zurück auf den ersten Arbeitsmarkt – Berufliche Wiedereingliederung
Authors: Janssen Christina
Published: May 2022

Die 30-jährige Michelle erlitt vor zwei Jahren eine Meningitis. Daraus resultierten vor allem Aufmerksamkeits- und Konzentrationsdefizite. Ihre Ergotherapeutin Christina Janssen hilft Michelle bei der Rückkehr auf den ersten Arbeitsmarkt – mit teilweise sehr einfallsreichen und originellen Maßnahmen.
First Clinical Study on Long-Acting Growth Hormone Therapy in
Children with Turner Sydrome
Authors: Gao Xinying , Chen Jiajia , Cao Bingyan , Dou Xinyu , Peng Yaguang , Su Chang , Qin Miao , Wei Liya , Fan Lijun , Zhang Beibei , Gong Chunxiu
Published: May 2022

Study on long-acting growth hormone (LAGH) therapy in Turner syndrome (TS) is a
2-year retrospective study including patients diagnosed with TS from
2018–2021. Patients were divided into four groups: Group 1 to 4 were low
dose (0.1 mg/kg/ w), high-dose
(0.2 mg/kg/w) LAGH, daily GH
(0.38 mg/kg/w), and untreated control. The efficacy and
safety data were analyzed. Seventy-five TS cases with the age 7.9±2.9
years and the bone age 6.8±2.8 years were recruited. In year 1: The
change of height standard deviation score (ΔHtSDS) and height velocity
(HV) in Group 2 were comparable to Group 3, both two groups were higher than
Group 1. ΔHtSDS and HV in all GH treatment group were higher than
untreated group. IGF1 increased in all treatment groups, only 4 cases had
IGF1>3 SD. In year 2: ΔHtSDS and HV in Group 2 and 3 were
comparable. Five cases had IGF1>3 SD. Correlation analysis for LAGH
efficacy at year 1 indicated that baseline variables correlated with
ΔHtSDS include: GH dose, CA (chronological age), and bone age (BA). The
HV was positively correlated with baseline GH dose, HtSDS, IGF-1SDS and
negatively correlated with baseline CA, BA, and BMI. No GH-related serious
adverse effects were observed. The high-dose LAGH treatment in TS patients is
effective and safe as daily GH for 2 years. The favorable prognosis factors
include sufficient GH dose and early treatment. IGF1 monitoring and weight
control are important.
Association of Changes in Thickness of Limbal Epithelial and Stroma with Corneal Scars Detected by High-Resolution Anterior Segment Optic Coherence Tomography
Authors: Guclu Hande , Sattarpanah Samira , Gurlu Vuslat
Published: May 2022

Aim To investigate the corneal central and limbal thickness in cornea scar patients using high-resolution anterior segment optical coherence tomography (AS-OCT) and to determine the changes in the limbal region due to the corneal scar. Also, to evaluate tear film parameters in scar patients.

Methods Thirty patients with central corneal scar and 30 control subjects. The control subjects were healthy individuals who came to our clinic for routine ophthalmological examination. They were enrolled in this matched case-control study. Central epithelial thickness (ET), stromal thickness (ST), limbal epithelial thickness (LET), and limbal stromal thickness (LST) were analyzed using high-resolution AS-OCT. For evaluation of the ocular surface, the following techniques were used: tear break-up time (BUT) employing standard sterile strips of fluorescein sodium, Schirmer test-I (SCH), and the Ocular Surface Disease Index (OSDI) Questionnaire.

Results The mean central ET of the patient group was 51.5 ± 12.4 µm, while the mean central ET of the control group was 59.2 ± 9.0 µm. There was a statistically significant difference between patients and controls (p = 0.008). The mean LST of the patients was 747.9 ± 115.7 µm, and the mean LST of the controls was 726.3 ± 79.7 µm. There was a statistically significant difference between patients and controls according to BUT (p = 0.009) and SCH (p = 0.04). However, there was no significant difference between OSDI results of patients and controls (p = 0.08).

Conclusion Corneal monitoring with high-resolution AS-OCT is a simple, noninvasive, useful technique for corneal scar patients. Cornea scars cause decreased ET. This result could be associated with lower tear film parameters in scar patients. The scar length is associated with higher intraocular pressure (IOP) values. Decreased LET and increased LST were detected in scar patients.
One-Pot Syntheses of Substituted 2-Aminothiazoles and 2-Aminoselenazoles via Meerwein Arylation of Alkyl Vinyl Ketones
Authors: Ostapiuk Yurii V. , Schmidt Andreas , Ostapiuk Mary Y. , Barabash Oksana V. , Kravets Mykola , Herzberger Colin , Namyslo Jan C. , Obushak Mykola D.
Published: May 2022

Both one-pot and two-step procedures for the synthesis of substituted 2-aminothiazoles and 2-aminoselenazoles are described. Anilines are first converted into arenediazonium bromides, which are then reacted with methyl vinyl ketone or cyclopropyl vinyl ketone in the presence of copper(II) bromide to give 4-aryl-3-bromobutan-2-ones (40–71%) and 3-aryl-2-bromo-1-cyclopropylpropan-1-ones (41–79%), respectively. These products are reacted, without prior isolation, with thiourea or selenourea to prepare 4-methyl- and 4-cyclopropyl-5-(R-benzyl)thiazol-2-amines (14 examples) and their selenium analogs (14 examples). The yields of the one-pot procedure are higher (40–81%) than those of the two-step procedure (32–70%).
A Study of Muscular Objective Tinnitus Caused by the Eustachian Tube
Authors: Mizuta Kunihiro , Endo Shiori , Arai Maki
Published: May 2022

Objective tinnitus that originates in muscles can be heard by others as well as by the patient. Although there have been many reports of objective tinnitus, each report has been limited to a small number of cases that have varied from one another, with some being accompanied by such findings as voluntary and/or involuntary movement of the soft palate and eardrum, as well by blinking, and the etiology has remained unclear. We analyzed 16 cases of objective tinnitus synchronous with the opening and closing of the eustachian tube. The voluntary and involuntary movements of the soft palate and eardrum were consistent with the findings in previous reports. The 16 cases included 11 cases of patulous eustachian tube and in 10 of them the patient voluntary induced tinnitus to prevent the symptoms of a patulous eustachian tube. These patients created an opportunity to close the patulous eustachian tube by repeating opening and closing. The sound of the opening and closing of the eustachian tube became an objective tinnitus. The tinnitus was heard only voluntary in seven cases and voluntary and involuntarily in nine cases; one of patients was tentatively diagnosed with middle ear myoclonus and another was diagnosed with pharyngolaryngeal myoclonus. Patulous eustachian tube was first described as one of the causes of objective tinnitus. We speculated that the soft palate and eardrum movements were initially voluntary, but that some of them became involuntarily. If this involuntary movement is seen at the time of examination, it may be diagnosed as myoclonus. Psychological factors may be involved in the transitions from voluntary to involuntary, but further research will be necessary to assess this possibility.
Could more noise mean better hearing?
Authors: Piccone Ashley
Published: May 2022

Adding noise to signals increases the amount of information transmitted to cochlear implant users, but does not increase their ability to identify vowel sounds
X-ray source design optimization using differential evolution algorithms—A case study
Authors: Yan Weizhong , Bai Ye , Xu Rui , Neculaes V. Bogdan
Published: May 2022

Traditional x-ray sources used today for multiple applications, such as medical imaging (computed tomography, radiography, mammography, and interventional radiology) or industrial inspection, are vacuum based electron beam devices that include several key components, such as electron emitters, electron guns/cathodes, and anodes/targets. The associated electronics for electron beam generation, focusing and control, and beam acceleration are located outside the vacuum chamber. The general topology of these tubes has been directionally unchanged for more than 100 years; however, tube design remains a long, inefficient, tedious, and complex process; blind design of experiments do not necessarily make the process more efficient. As a case study, in this paper, we introduce the differential evolution (DE), an artificial intelligence-based optimization algorithm, for the design optimization of x-ray source beam optics. Using a small-scale design problem, we demonstrate that DE can be an effective optimization method for x-ray source beam optics design.
In situ measurements of electrical resistivity of metals in a cubic multi-anvil apparatus by van der Pauw method
Authors: Yang Fan , Hu Xiaojun , Fei Yingwei
Published: May 2022

On the basis of the van der Pauw method, we developed a new technique for measuring the electrical resistivity of metals in a cubic multi-anvil high-pressure apparatus. Four electrode wires were introduced into the sample chamber and in contact with the pre-pressed metal disk on the periphery. The sample temperature was measured with a NiCr–NiSi (K-type) thermocouple, which was separated from the sample by a thin hexagonal boron nitride layer. The electrodes and thermocouple were electrically insulated from each other and from the heater by an alumina tube as well. Their leads were in connection with cables through the gap between the tungsten carbide anvils. We performed experiments to determine the temperature dependence of electrical resistivity of pure iron at 3 and 5 GPa. The experiments produce reproducible measurements and the results provide an independent check on electrical resistivity data produced by other methods. The new technique provides reliable electrical resistivity measurements of metallic alloys and compounds at high pressure and temperature.
Strain-rate correlation of biaxial tension and compression mechanical properties of HTPB and NEPE propellants
Authors: Wang Qizhou , Wang Guang , Wang Zhejun , Qiang Hongfu , Wang Xueren , Pei Shudi
Published: May 2022

An effective biaxial tension and compression test method is proposed based on the shortcomings of current research for the mechanical properties of solid propellants under complex stress states. The equal proportion biaxial tension and compression test of HTPB (Hydroxyl-terminated polybutadiene) and NEPE (NitrateEster Plasticized Polyether) solid propellants is performed at different rates while at room temperature, and the damage morphology of the tension–compression zone is analyzed using micro-CT. The results show that the failure mode of the solid propellant under biaxial tension and compression loading is similar to that under uniaxial tension. Meanwhile, the compressive strength is much greater than the tensile strength, which will eventually cause tensile failure. With an increased loading rate, the growth trend of the initial modulus, ultimate strength, and maximum elongation of the propellant is gradually flattened, and the damage degree is gradually reduced. Additionally, damage that forms in the HTPB propellant is from dewetting and particle fracture while that for the NEPE propellant is from matrix tearing. The porosity can be used as the meso-damage parameter of the propellant.
Strategies for accessing photosensitizers with extreme redox potentials
Authors: Kim Dooyoung , Teets Thomas S.
Published: May 2022

Photoredox catalysis has been prominent in many applications, including solar fuels, organic synthesis, and polymer chemistry. Photocatalytic activity directly depends on the photophysical and electrochemical properties of photocatalysts in both the ground state and excited state. Controlling those properties, therefore, is imperative to achieve the desired photocatalytic activity. Redox potential is one important factor that impacts both the thermodynamic and kinetic aspects of key elementary steps in photoredox catalysis. In many challenging reactions in organic synthesis, high redox potentials of the substrates hamper the reaction, leading to slow conversion. Thus, the development of photocatalysts with extreme redox potentials, accompanied by potent reducing or oxidizing power, is required to execute high-yielding thermodynamically demanding reactions. In this review, we will introduce strategies for accessing extreme redox potentials in photocatalytic transformations. These include molecular design strategies for preparing photosensitizers that are exceptionally strong ground-state or excited-state reductants or oxidants, highlighting both organic and metal-based photosensitizers. We also outline methodological approaches for accessing extreme redox potentials, using two-photon activation, or combined electrochemical/photochemical strategies to generate potent redox reagents from precursors that have milder potentials.
Study on the magneto-Rayleigh–Taylor instability of inverse exploding planar foils
Authors: Liu Yongtang , Sheng Liang , Li Yang , Zhang Jinhai , Li Haoqing , Yuan Yuan , Ouyang Xiaoping
Published: May 2022

Experiments of the explosion of thin planar foils have been carried on the QiangGuang-I facility (∼1.4 MA peak current, ∼110 ns rise time) to study the evolution of the plasma instability. An inverse-field configuration was utilized with the current return post placed in the center and two parallel planar aluminum foils of 20 μm thickness, 1 cm width built on each side. The foil was ablated into a plasma slab with a particular width, and the inner surface and outer surface expanded in opposite directions and suffered from unequal magnetic pressure, resulting in divergent instability evolution. To alter plasma acceleration, multiple load configurations, including symmetric and asymmetric cases, were used to change the distance between the foil and back-post. The diagnostic system was fielded to provide a side-on view of exploding foils, including laser shadowgraphy, laser interferometry, and an optical framing camera. The characteristic structure, wavelength spectrum, and growth rate of the instability were compared for both sides. During the early magnetohydrodynamics instability developing stage, the inner side had a similar feature to the outer side surface, but with a larger ratio of the long wavelength in the spectrum. The anti-correlated relationship between the correlation coefficients of two surfaces appeared to be a kink instability mode. When the interface was subjected to deceleration, a transition from an early instability mode to a Magneto-Rayleigh–Taylor (MRT) instability mode was observed in studies, with the growth rate and characteristic wavelength growing fast. Because of the higher magnetic pressure and earlier retardation, the inner edge was more severely affected by MRT instability than the outer edge. A theoretical model was developed to interpret the experimental data.
High extinction ratio thermo-optic based reconfigurable optical logic gates for programmable PICs
Authors: Hassan S. , Chack D. , Pavesi L.
Published: May 2022

In this paper, a new scheme is proposed to realize reconfigurable and multifunction optical logic gates (XOR, XNOR, NAND, and OR) using a Mach–Zehnder interferometer with a tunable thermo-optic phase shifter (TOPS). The reconfigurable optical logic gates are realized by tuning the phase of an optical signal using TOPS without changing the physical device structure. The logical input “0” or “1” is considered corresponding to the phase of the optical signal at TOPS. The logical output of the proposed device depends on the light intensity at output ports. The device is designed on silicon on insulator (SOI) platform and the simulation result shows that the on–off extinction ratio is greater than 37 dB at 1550 nm and >25 dB for the C-band. Moreover, it has a low insertion loss of 0.09 dB at a wavelength of 1550 nm and <0.8 dB for the C-band window. The proposed optical logic gates can be a promising logical device for programmable photonic integrated circuits.
A multi-feature predicting model of crown evolution involving material properties
Authors: Ma Tianyu , Cao Yanchuang , Liu Jun , Xu Aiguo , Chen Jie , Jia Yingqi , Chen Dawei
Published: May 2022

We propose a new model for the crown evolution after a single drop impacts on a thin film. In contrast with the existing models that mainly focus on the status of well-developed crown or the bottom radius evolution, multiple features are provided in our model, including the temporal evolution of the crown radius, height, velocity, and the characteristic time when the crown reaches its maximum height. Both the fluid viscosity and surface tension are considered in this work rather than ignoring one or both of them as in previous studies, resulting in improved accuracy for crown development prediction. The new model can be applied for droplets of various fluids impinging on relatively thin films (0.1 < δ < 0.67). The reliability of the model is validated via comparing results with five cases of droplet impact experiments.
Active polar flock with birth and death
Authors: Mishra Pawan Kumar , Mishra Shradha
Published: May 2022

We study a collection of self-propelled polar particles on a two-dimensional substrate with birth and death. We introduce a minimal lattice model for the system using active Ising spins, where each particle can have two possible orientations. The activity is modeled as a biased movement of the particle along its direction of orientation. The particles also align with their nearest neighbors using Metropolis Monte Carlo algorithm. The system shows a disorder-to-order transition by tuning the temperature of the system. Additionally, the birth and death of the particles is introduced through a birth and death parameter γ. The system is studied near the disorder-to-order transition. The nature of disorder-to-order transition shows a crossover from the first order, discontinuous to continuous type as we tune γ from zero to finite values. We also write the effective free energy of the local order parameter using perturbative calculation, and it confirms the dependence of the nature of phase transition on the birth and death parameter.
Broadband terahertz time-domain polarimetry based on air plasma filament emissions and spinning electro-optic sampling in GaP
Authors: Xu Kuangyi , Liu Mengkun , Arbab M. Hassan
Published: May 2022

We report on a time-domain polarimetry (TDP) system for generating and detecting broadband terahertz (THz) waves of different polarization angles. We generate THz waves from two-color laser filaments and determine their polarization states with a detection bandwidth of up to 8 THz using a spinning gallium phosphide crystal. The polarization of THz emission can be controlled by adjusting the position and tilt angle of the β-barium borate crystal. We characterize the precision of this system for polarimetric measurements at fixed time delay to be 1.6° and 1.9° for complete time-domain waveforms. We also demonstrate the feasibility of our TDP system by measuring broadband optical properties of anisotropic samples in both transmission and reflection geometries. The THz-TDP technique can be easily integrated in conventional THz time-domain spectroscopy setups using nonlinear crystal detectors.
Experimental study on the ignition process of a pulsed capacitively coupled RF discharge: Effects of gas pressure and voltage amplitude
Authors: Wang Xiang-Yu , Wang Xiao-Kun , Zhao Kai , Liu Yong-Xin , Wang You-Nian
Published: May 2022

The effects of gas pressure and voltage amplitude on the ignition process of a pulse capacitively coupled RF argon discharge are experimentally investigated. The electron density is measured by a hairpin probe, the spatiotemporal distribution of the electron impact excitation dynamics is determined by phase resolved optical emission spectroscopy, and the electrical parameters are obtained by analyzing the measured current and voltage waveforms. In this work, the pulse plasma is ignited with few initial electrons, so the ignition process behaves like gas breakdown. Based on the measured RF breakdown curve, the gas pressures and voltage amplitudes are selected, and then different characteristics of ignition processes are compared and discussed in detail. Particularly, the spatiotemporal pattern of the electron impact excitation rate obtained within the selected pressure range, as well as other results, aid the intuitive understanding of a typical “V-shaped” RF breakdown curve. At lower pressures, the excitation pattern exhibit shorter and tilted regions, ending at electrodes during the early ignition stage, implying a substantial electron energy loss, while at relatively high pressures, the excitation pattern becomes wider and less tilted, and the proportion of electron energy consumed by excitation processes increases. In addition, by increasing the voltage amplitude, the ignition is advanced and becomes more significant, manifesting a faster increase in discharge current and a stronger overshoot of RF power deposition. Meanwhile, at high voltage amplitude, the excitation pattern exhibits complex spatiotemporal distribution due to enhanced local electric field when the plasma emission intensity overshoots.
MoS2/SnO2 heterojunction-based self-powered photodetector
Authors: Augustine Pius , Kumawat Kishan Lal , Singh Deependra Kumar , Krupanidhi Saluru Baba , Nanda Karuna Kar
Published: May 2022

A heterostructure of MoS2/SnO2 has been fabricated. A SnO2 film was deposited by Sn sputtering followed by oxidation of a Sn film in the ambient. Later, a MoS2 film was deposited on SnO2 by pulsed laser deposition. The built-in electric potential generated at the SnO2/MoS2 interface facilitates self-powered broadband photodetection ranging from the ultraviolet-visible to near-infrared (NIR) wavelength. Under NIR illumination, the device exhibits excellent photoresponse with a responsivity of 0.35 A W−1 and a detectivity of 1.25 × 1011 Jones at 0 V. Moreover, the device shows faster response with rise/fall times as 153/200 ms. The excellent performance of the device is attributed to the high electron transport behavior of SnO2 and a built-in electric field at the interface.
On the generation and destruction mechanisms of arch vortices in urban fluid flows
Authors: Lazpita Eneko , Martínez-Sánchez Álvaro , Corrochano Adrián , Hoyas Sergio , Le Clainche Soledad , Vinuesa Ricardo
Published: May 2022

This study uses higher-order dynamic mode decomposition to analyze a high-fidelity database of the turbulent flow in an urban environment consisting of two buildings separated by a certain distance. We recognize the characteristics of the well-known arch vortex forming on the leeward side of the first building and document this vortex's generation and destruction mechanisms based on the resulting temporal modes. We show that the arch vortex plays a prominent role in the dispersion of pollutants in urban environments, where its generation leads to an increase in their concentration; therefore, the reported mechanisms are of extreme importance for urban sustainability.
Tuning the coercivity of ferromagnetic films with perpendicular anisotropy by thickness, width, and profile
Authors: Kopnov G. , Gerber A.
Published: May 2022

The coercive field of laterally heterogeneous CoPd films with perpendicular magnetic anisotropy was found to be highly sensitive to their nominal thickness and morphology in the vicinity of the metal–insulator transition. We used the effect to tune the coercivity by the width of lithographically patterned stripes with non-uniform cross-sectional thickness profiles. The phenomenon and the method can be suitable to control the local anisotropy of spintronic logic circuitry elements by their shape and lateral dimensions.
Local analysis of fast magnetic reconnection
Authors: Boozer Allen H.
Published: May 2022

Fast magnetic reconnection is defined by the topology of the magnetic field lines changing on a timescale that is approximately an order of magnitude longer than the topology-conserving ideal-evolution timescale. Fast reconnection is an intrinsic property of Faraday's law when the evolving magnetic field depends non-trivially on all three spatial coordinates and is commonly observed—even when the effects that allow topology breaking are arbitrarily small. The associated current density need only be enhanced by a factor of approximately ten and flows in thin but broad ribbons along the magnetic field. These results follow from the variation in the separation of neighboring pairs of magnetic field lines, which in an ideal evolution typically increases exponentially with time, and the existence of a spatial scale below which magnetic field lines freely change their identities due to non-ideal effects, such as resistivity. Traditional reconnection theory ignores exponentially large variations and relies on the current density reaching a magnitude that is exponentially larger than is actually required. Here, an analysis of the behavior of magnetic field lines in the neighborhood of an arbitrarily chosen line is used to obtain more precise and rigorous results on intrinsic reconnection. The maximum parallel kinetic energy of collisionless charged particles is shown to have an exponential increase in time during a generic magnetic evolution.
Direct observation of spin polarization in epitaxial Fe3O4(001)/MgO thin films grown by magnetron sputtering
Authors: Zhang Zhe , Lu Xianyang , Yan Yu , Lu Jiahua , Li Zhuoyi , Liu Qi , Zhu Fangyuan , Cao Jiefeng , Wang Yong , Huang Zhaocong , Zhai Ya , Li Yao , Ruan Xuezhong , He Liang , Wu Jing , Du Jun , Zhang Rong , Xu Yongbing
Published: May 2022

We obtained epitaxial single-crystal Fe3O4(001)/MgO(001) thin films by magnetron sputtering. The high quality of the grown Fe3O4 films was confirmed by reflection high-energy electron diffraction and x-ray photoelectron spectroscopy. Atomic magnetic properties of Fe3O4(001)/MgO(001) were investigated using vibrating sample magnetometry and x-ray magnetic circular dichroism. The values of saturation magnetization and magnetic moment are 407 ± 5 emu/cm3 (3.26 ± 0.04 μB/(f.u.)) and 3.31 ± 0.15 μB/(f.u.), respectively, in the Fe3O4 film as thin as 5 nm, which are close to the bulk values. The spin polarization was directly measured using spin-resolved photoemission spectroscopy. The measured spin polarization has a maximum value of −42% ± 3%, which is comparable to the theoretical value for the (2 × 2)R45° reconstructed Fe3O4(001) surface. Furthermore, the film thickness-dependent measurements indicate that the anti-phase boundaries significantly decrease the spin polarization rather than the lattice mismatch. Our results demonstrate that epitaxial Fe3O4(001)/MgO thin films grown by magnetron sputtering have desired magnetic properties, facilitating the potential application of Fe3O4-based spintronic devices.
Two-level gas laser with transverse diode pumping
Authors: Parkhomenko A.I. , Shalagin A.M.
Published: May 2022

We theoretically study a new method for generating laser radiation by a two-level system without population inversion in the ‘red’ wing of its spectral line under resonant absorption of broadband radiation from pump laser diodes. A two-level system simulates the atoms of an active gas in an atmosphere of a high-pressure buffer gas. The effect results from the fact that in the ‘red’ wing of the spectral line, the probability of stimulated emission exceeds the probability of absorption if the homogeneous broadening due to the interaction of particles with the buffer gas significantly exceeds the natural one (at high pressures of the buffer gas). Analytical formulae are obtained that describe the operation of a two-level gas laser with transverse diode pumping. It is found that the longer the active medium, the higher the buffer gas pressure and pump radiation intensity, and the smaller the width of the pump radiation spectrum, the greater the efficiency of conversion of pump radiation into laser radiation. In a sufficiently long active medium (the length of the medium is 50 times its width), the conversion efficiency can reach 44 % at a buffer gas pressure of 5 atm, a pump diode radiation intensity of 3 kW cm−2, and a half-width of its spectrum of 1 cm−1. A two-level gas laser with transverse diode pumping is capable of generating continuous optical radiation with a very high (up to 100 kW) power. The frequency of laser radiation can be tuned by several tens of cm−1.
Specific features of radiation flux formation in diode-pumped lasers and amplifiers with active elements made of Nd : YAG ceramics
Authors: Bogdanovich M.V. , Dudikov V.N. , Lepchenkov K.V. , Loiko V.A. , Popov Yu.M. , Ryabtsev A.G. , Ryabtsev G.I. , Shpak P.V. , Shchemelev M.A.
Published: May 2022

The spatial, temporal, and spectral characteristics of the output radiation of diode-pumped laser systems and optical amplifiers with active elements made of Nd : YAG ceramics are studied. It is shown that the divergence of radiation in the subthreshold regime has the form of concentric nested cones emerging from the active element (AE) faces at angles of 2 – 4 °. A model explaining the experimentally observed phenomenon is proposed based on the mechanism of scattering of the generated beam from the granular structure of the optical ceramics. Analysis of the divergence pattern makes it possible to estimate the grain size and the optical quality of ceramics. The output beam divergence in the lasing regime is determined mainly by the cavity parameters and does not exceed several milliradians. The scattering events in this case serve as sources of additional optical losses. Luminescence enhancement and parasitic oscillations in the AE volume restrict the possibility of using Nd : YAG ceramics for fabricating AEs of high-power optical amplifiers.
Generation and dynamics of wave packets with a large phase modulation depth
Authors: Abramov A.S. , Zolotovskii I.O. , Korobko D.A. , Kamynin V.A. , Ribenek V.A. , Fotiadi A.A. , Tsarev V.S.
Published: May 2022

This paper examines the generation of high-frequency picosecond pulse trains as a result of modulation instability of wave packets with a large phase modulation depth and small amplitude modulation depth. We demonstrate that intermediate amplification of such wave packets and subsequent phase-to-amplitude modulation conversion lead to the formation of pulses with peak powers orders of magnitude higher than their initial power. The corresponding pulse generators can be used to generate a line spectrum.
Superluminescence in the phonon wing of the photoluminescence spectrum of NV centres in diamond optically pumped at λ = 532 nm
Authors: Lipatov E.I. , Genin D.E. , Shulepov M.A. , Tel’minov E.N. , Savvin A.D. , Eliseev A.P. , Vins V.G.
Published: May 2022

Superluminescence of NV centres with a band peaking at λ = 718 nm in the phonon wing of the photoluminescence spectrum of a high-pressure high-temperature (HPHT) diamond sample under pulsed optical excitation at λ = 532 nm with an intensity of 2 – 46 MW cm−2 is demonstrated. Superluminescence is observed in the diamond crystal region containing 6 ppm NV centres and 150 ppm substituent nitrogen; it is absent in the crystal part with a lower nitrogen content. Superluminescence pulses are observed on the leading edge of the optical excitation pulse at λ = 532 nm and have an FWHM value of 4 ns. The enhancement of the photoluminescence of NV centres is suggested to be due to the total internal reflection in the diamond plate (waveguide effect).
Complementary feedback control enables effective gaze stabilization in animals
Authors: Cellini Benjamin , Salem Wael , Mongeau Jean-Michel
Published: May 2022

Significance

In visually active animals, eye, head, and body movements are coordinated to direct gaze. Given their distinct mechanics, how does the nervous system weight their contribution? By combining experiments in flying flies with control theory, we show that flies implement an elegant solution to this problem: the lower inertia head is recruited for higher-frequency visual tasks and is sensitive to motion acceleration, whereas the higher inertia body is recruited for lower-frequency visual tasks and is sensitive to motion velocity. This complementary division of labor within the nervous system exhibits two hallmarks of optimality: an increase in task performance accompanied with a decrease in mechanical energy expenditure. Our model recapitulates classic primate head-eye coordination responses, suggesting convergent mechanisms across phyla.
Caused accompanied motion constructions in Vera’a
Authors: Schnell Stefan
Published: May 2022

The expression of bring and take events (so-called ‘caused accompanied motion (CAM)’ events) in the Oceanic language Vera’a (North Vanuatu) is analysed in terms of lexical and constructional compositionality. The two lexical verbs centrally involved in CAM expressions have fairly general semantic content not specific to CAM events, meaning ‘move sth.’ and ‘accompany’. These are used in constructional frames with dative and locative prepositions, serialization with verbs of motion, and directional adverbs and particles. Such constructions can then yield a CAM reading. However, they can also receive a non-CAM reading, so that the verbalisation of CAM events is ultimately a matter of pragmatic inference in Vera’a and never unambiguously encoded. Different verbs are used to specify manner of handling themes, and manner of motion as well as direction can be incorporated in motion verbs in initial position of verb serialization (satellite-framed).
Expressions of directed caused accompanied motion in Komnzo
Authors: Döhler Christian
Published: May 2022

This chapter describes and analyses the expression of directed caused accompanied motion (directed CAM) in Komnzo, a language of Southern New Guinea. The chapter focusses on the interaction between lexical semantics and verb morphology. It shows that the expression of CAM events revolves around a handful of very frequent lexical items (carry, fetch, return verbs), which can be placed in different morphological templates. Morphological fluidity provides a productive mechanism to derive causative alternations of intransitive motion verbs, i.e. an intransitive return verb can be used to express ‘return something’. The chapter adopts a corpus linguistic approach to the phenomenon of CAM events by providing a fine-grained frequency analysis of the most important verb lexemes based on the Komnzo text corpus. Additionally, the chapter describes how the system of adverbial demonstratives and case markers contribute to expression of CAM events.
Microstructure and mechanical property of titanium steel by vacuum roll-cladding with interlayer
Authors: Zhao Jia-xiang , Luo Zong-an , Wang Ming-kun , Xie Guang-ming , Xv Jian-ping
Published: May 2022

The titanium clad steel plates were prepared by vacuum roll-cladding (VRC) in three ways: without interlayer, with Fe interlayer and Ni interlayer. With the increase in temperature, the TiC layer becomes thicker and the metal compounds increase at the interface during VRC without interlayer. The bonding strength is 266 MPa at 900°C. The Fe interlayer effectively inhibits the diffusion of C element and reduces the amount of TiC. The fracture is brittle and partial ductile, and the interface bonding strength improved. The Ni interlayer can prevent the interdiffusion of Ti and Fe elements, but brittle TiC and Ti-Ni compounds are formed at the interface. The bonding strength is low, and the fracture is brittle, which occurs at the Ti-Ni interface.
Maximizing the rate sensitivity of resonating gyroscopes using nonlinear shape optimization
Authors: Polunin Pavel M , Shaw Steven W
Published: May 2022

In this work we demonstrate how one can improve the angular rate sensitivity of ring/disk resonating gyroscopes by tailoring their nonlinear behavior by systematic shaping of the gyroscope body and electrodes, and by the tuning of bias voltages on segmented electrodes. Of specific interest are the drive and sense mode Duffing nonlinearities, which limit their dynamic ranges, and the intermodal dispersive coupling between these modes that provides parametric amplification of the sense mode output signal. These two effects have the same physical origins and are in competition in terms of system performance, which naturally calls for optimization considerations. The present analysis is based on a systematic modeling of the nonlinear response of these devices by which we explore ways in which one can optimize the angular rate sensitivity by manipulating the mechanical and electrostatic contributions to the nonlinearities. In particular, non-uniform modifications of the gyroscope body thickness are employed to affect the mechanical contributions to these parameters, while the electrostatic components are manipulated via shaping of the resonator-electrode gap and by applying non-uniform bias voltages among segmented electrodes around the gyroscope body. These models predict that such relatively simple alterations can achieve improvements in gain by about an order of magnitude when compared to devices with uniform layouts.
γ–α phase transition of elemental cerium metal
Authors: Eryigit Serpil , Parlak Cihan , Eryigit Resul
Published: May 2022

The isostructural γ–α phase transition in elemental cerium has been the subject of many experimental and theoretical studies over almost the past century without a universally agreed upon mechanism. Here, we report the results of an extensive study of electronic and magnetic structures, f-electron number, entanglement entropy, and elastic properties of cerium in the GGA + U framework. We have found that almost all changes in the studied quantities mimic their behavior in the phase transition and could be related to the symmetry of the 4f occupation and the small change in Hubbard U near a critical value.