bluuebunny/crossref_metadata_2025 huggingface dataset:
Supersonic jet by blast wave focusing
Authors: Apazidis N. , Sembian S. , Liverts M.
Published: December 2021

A supersonic jet of Mach number M = 4.5 in air is produced experimentally at the apex of a miniature 150 × 50 × 5 mm converging section with a 2 × 5 mm opening by the principle of blast wave amplification through focusing. An initial plane blast wave of M = 2.4 in the convergence section is generated by the exploding wire technique. The profile of the convergence section is specially tailored to smoothly transform a plane blast wave into a perfectly cylindrical arc, imploding at the apex of the section. The cylindrical form of the imploding shock delivers maximum shock amplification in the two-dimensional test section and maximum subsequent jet flow velocity behind the shock front. Blast wave propagation in the convergence chamber as well as jet generation through a 2 mm opening at the apex into the adjacent exhaust chamber is optically captured by a high-speed camera using the shadowgraph method. Visualizing the flow provided a distinct advantage not only for obtaining detailed information on the flow characteristics but also for validating the numerical scheme which further enhanced the analysis. Experimental images together with the numerical analysis deliver detailed information on the blast wave propagation and focusing as well as subsequent jet initiation and development. One of the main advantages of the described method apart from being simple and robust is the effective focusing of low initial input energy levels of just around 500 Joules, resulting in production of supersonic jets in a small confined chamber.
Mode transformations of vortex shedding behind a sphere with the effect of Lorentz force
Authors: Yao Weiguang , Zhang Hui , Jiang Daiwen , Gui Mingyue , Zhao Zijie , Chen Zhihua
Published: December 2021

In this paper, the modes of vortex shedding in the wake of a stationary sphere with the Lorentz force, which can be generated by the actuators in weakly conductive fluids and is parallel to the sphere surface, are numerically investigated at Re = 300. The relations among the wake structures, the vorticity distribution, and the motions of the rear stagnation point and the separation point are discussed before and after the application of Lorentz force. From this, the mechanism of mode transformations in the sphere wake is revealed. The results indicate that the fluid near the sphere surface is accelerated with the application of Lorentz force. The rear stagnation point and the separation point move rearward and become steady. Therefore, the vorticity on the rear surface of the sphere gradually decays and becomes steady, which leads to the periodic shedding mode of hairpin vortex replaced by the steady double-thread wake structure. Moreover, the wake structure varies with the interaction parameter N of the Lorentz force. When the Lorentz force is relatively small (N = 0.04), the vibration amplitude of hairpin vortex is weakened, and the vortex heads disappear with vortex legs and necks left. The wake is still periodic due to the hairpin vortex shedding. As N increases to 0.08, the hairpin vortex is suppressed completely, while the double-thread wake appears. The wake is steady due to the suppression of the hairpin vortex shedding. As N further increases to 0.20, a spanwise vortex ring is formed around the double-thread wake.
Mode switch in tonal under-expanded impinging jets
Authors: Liu Nian-Hua , Li Xiang-Ru , Hao Peng-Fei , Zhang Xi-Wen , He Feng
Published: December 2021

The dominant resonance mode switch pattern concerning nozzle pressure ratio and impinging distance for under-expanded jets issuing from a convergent nozzle and impacting a flat surface is demonstrated for the first time. Schlieren visualization and acoustic measurements have been carried out to simultaneously capture the dynamic and acoustic properties of impinging jets with a nozzle pressure ratio ranging from 2.00 to 4.30 (from moderately under-expanded to highly under-expanded) and an impingement distance extent 3.0D to 11.0D, where D is the nozzle exit diameter. Five bands within which symmetric mode predominates have been discovered. Jets within these bands also exhibit high amplitudes in overall sound pressure level. Besides, dominant frequencies within any band remain relatively stable when impinging distance is fixed, while a negative correlation between dominant frequencies and impingement distance has been found. Dynamic mode decomposition has been applied to schlieren snapshot sequences to achieve dimension reduction, by which the sound source location of tones can be determined. It is found that symmetric mode finds its genesis near the impingement surface, whereas the source related to asymmetric mode lies in the shear layer near the third shock cell or the standoff shock, depending on the number of shock cells between the nozzle exit and the impinging surface. This difference in acoustic feedback paths serves as the cause of the mode switch. Further, the symmetric mode's source location's stability results in the stability of dominant frequencies within a band when impinging distance is fixed.
Control of the turbulent wake flow behind a circular cylinder by asymmetric sectoral hydrophobic coatings
Authors: Lebedev Anatoliy , Dobroselsky Konstantin , Safonov Alexey , Starinskiy Sergey , Sulyaeva Veronica , Lobasov Aleksei , Dulin Vladimir , Markides Christos N.
Published: December 2021

We demonstrate that sectoral coating by a hydrophobic fluoropolymer is an effective method for controlling flow separation and the turbulent wake behind a cylinder in high Reynolds number flows (Re = 2.2 × 105). Time-resolved particle image velocimetry measurements show that the shape of the wake and trajectory of large-scale vortex structures are inclined due to delayed flow separation on one side of the cylinder. Near-wall, high-resolution visualization reveals that this effect is related to micro-bubbles traveling along the coated surface. The properties of the coatings and bubble presence did not deteriorate, even after many hours of continuous facility operation.
Biological tissues as mechanical metamaterials
Authors: Parker Amanda
Published: December 2021

How can researchers geometrically tune the extent to which a material embodies a stiff or flexible structure?
Diversity for morphological traits, flowering time and leaf isoflavone content among ecotypes of
Authors: Enkhbat Gereltsetseg , Nichols Phillip G. H. , Foster Kevin J. , Ryan Megan H. , Inukai Yoshiaki , Erskine William
Published: December 2021

Trifolium subterraneum L. subsp. yanninicum is a pasture legume that is widely grown in medium and high rainfall areas of southern Australia and shows waterlogging tolerance. This study investigated diversity within subsp. yanninicum corresponding to eco-geographic variables, which may help to identify adapted parents with new traits for genetic improvement. Diversity for 10 morphological traits, flowering time and leaf isoflavone content was investigated using 108 ecotypes derived from wild Mediterranean populations and 10 cultivars, grown as spaced plants. Among the ecotypes, the range of flowering time was 94–149 days after sowing, and contents of formononetin, genistein and biochanin A were 0.05–1.38%, 0.73–2.33% and 0.15–2.10% of dry matter, respectively. Leaf markings also varied considerably. Leaf size and petiole length were correlated at each growth stage. Later flowering genotypes had larger leaves, longer petioles, longer internodes and thicker stems at flowering, but smaller leaves and shorter petioles at both 63 and 88 days after sowing. Contents of genistein and biochanin A were unrelated, but both were negatively associated with formononetin. Flowering time had a weak positive influence on genistein and biochanin A, but a weak negative influence on formononetin. All traits among the ecotypes (except stem diameter and leaf mark crescent size) were significantly correlated with at least one of 22 eco-geographic variables from their collection sites. Precipitation and altitude were more influential than temperature. The study found sufficient diversity to broaden the narrow genetic base of current subsp. yanninicum cultivars; however, other agronomically important traits also need to be considered. Further diversity may result from targeted collection, particularly in areas not represented in annual legume genebanks.
Topological liquid crystal superstructures as structured light lasers
Authors: Papič Miha , Mur Urban , Zuhail Kottoli Poyil , Ravnik Miha , Muševič Igor , Humar Matjaž
Published: December 2021

Significance

Liquid crystals (LCs) are used in a number of optical devices including lasers. However, until now, only relatively simple LC structures have been employed inside laser cavities. LCs enable the self-assembly of extremely complex birefringent structures, which would be impossible to manufacture in any other way. LC molecules also orient the emission dipoles of the dye, delivering efficient gain only to modes with the desired polarization. Further, due to sensitivity of the LCs to external stimuli, they enable large tunability. This study provides experimental and simulation insights into coupling of light with the complex LC topological superstructures inside a laser cavity, realizing nontrivial intensity and polarization of the generated structured light.
Utilising design principles to improve the perception and effectiveness of public health infographics
Authors: Baxter Matthew , Lonsdale Maria dos Santos , Westland Stephen
Published: December 2021

Infographics are becoming a common tool in the communication of public-health information. However, research-based resources in how to create effective infographics are rare. The application of design principles in the creation of infographics has been shown to more effectively communicate information. Here, the research explores the adherence of 84 research-based infographic design principles on 3 designs of varying levels of application. A multi-method approach, including eye-tracking, was used to record information location efficiency, memorability and user perception. Support was found in favour of utilising design principles in the creation of public health infographics; resulting in improved user opinion and information location.
Finding pythons in unexpected places
Authors: Engelhardt Netta , Penington Geoff , Shahbazi-Moghaddam Arvin
Published: December 2021

We argue that novel (highly nonclassical) quantum extremal surfaces (QESs) play a crucial role in reconstructing the black hole interior even for isolated, single-sided, non-evaporating black holes (i.e. with no auxiliary reservoir). Specifically, any code subspace where interior outgoing modes can be excited will have a QES in its maximally mixed state. We argue that as a result, reconstruction of interior outgoing modes is always exponentially complex. Our construction provides evidence in favor of a strong python’s lunch proposal: that nonminimal QESs are the exclusive source of exponential complexity in the holographic dictionary. We also comment on the relevance of these QESs to the geometrization of state dependence in the typicality arguments for firewalls.
Shadow and deflection angle of charged rotating black hole surrounded by perfect fluid dark matter
Authors: Atamurotov Farruh , Papnoi Uma , Jusufi Kimet
Published: December 2021

We analysed the shadow cast by charged rotating black hole (BH) in presence of perfect fluid dark matter (PFDM). We studied the null geodesic equations and obtained the shadow of the charged rotating BH to see the effects of PFDM parameter γ, charge Q and rotation parameter a, and it is noticed that the size as well as the shape of BH shadow is affected due to PFDM parameter, charge and rotation parameter. Thus, it is seen that the presence of dark matter around a BH affects its spacetime. We also investigated the influence of all the parameters (PFDM parameter γ, BHs charge Q and rotational parameter a) on effective potential, energy emission by graphical representation, and compare all the results with the non rotating case in usual general relativity. To this end, we have also explored the effect of PFDM on the deflection angle and the size of Einstein rings.
Influence of geometry on positron binding to molecules
Authors: Danielson J R , Ghosh S , Surko C M
Published: December 2021

Annihilation studies have established that positrons bind to most molecules. They also provide measurements of the positron-molecule binding energies, which are found to vary widely and depend upon molecular size and composition. Trends of binding energy with global parameters such as molecular polarizability and dipole moment have been discussed previously. In this paper, the dependence of binding energy on molecular geometry is investigated by studying resonant positron annihilation on selected pairs of isomers. It is found that molecular geometry can play a significant role in determining the binding energies even for isomers with very similar polarizabilities and dipole moments. The possible origins of this dependence are discussed.
A confined carbon dot-based self-calibrated fluorescence probe for visible and highly sensitive moisture readouts
Authors: Ding Zhong-Zheng , Zheng Guang-Song , Lou Qing , Han Jiang-Fan , Wu Meng-Yuan , Shen Cheng-Long , Zang Jin-Hao , Liu Kai-Kai , Dong Lin , Shan Chong-Xin
Published: December 2021

Excellent luminescent materials are essential for high-performance fluorescent nanosensors. Here, a new-type of self-calibrated humidity sensor is established through monitoring the fluorescent color change of carbon dots (CDs) confined in sodium hydroxide (CDs@NaOH). The CDs are prepared by a facile and rapid microwave-assisted heating method using citric acid, urea, and NaOH as precursors. The confinement effect from the NaOH reduces the nonradiative transition and suppresses the aggregation-induced quenching of the CDs in the solid. Compared with other sensors based on CD fluorescent visualization, the sensor has good linearity and a wide humidity-detection range from 6.9% to 95.4%. With the increased relative humidity, the fluorescence color of the sensor changes from green to blue. The proposed sensing mechanism is due to the breaking and reforming of hydrogen bonds and proton transfer occurring at the CD-NaOH matrix interfaces. These findings suggest a potential role for the spatial confinement effect and may provide an avenue for developing highly sensitive humidity readouts.
Improvement of crystal quality and surface morphology of Ge/Gd2O3/Si(111) epitaxial layers by cyclic annealing and regrowth
Authors: Nanwani Alisha , Pokharia Ravindra Singh , Schmidt Jan , Osten H J , Mahapatra Suddhasatta
Published: December 2021

The role of post-growth cyclic annealing (PGCA) and subsequent regrowth, on the improvement of crystal quality and surface morphology of (111)-oriented Ge epitaxial layers, grown by low temperature (300 °C) molecular beam epitaxy on epi-Gd2O3/Si(111) substrates, is reported. We demonstrate that PGCA is efficient in suppressing rotational twins, reflection microtwins and stacking faults, the predominant planar defect types in Ge(111) epilayers. Continuing Ge growth after PGCA, both at low (300 °C) and high (500 °C) temperatures, does not degrade the crystal quality any further. By promoting adatom down-climb, PGCA is observed to also heal the surface morphology, which is further improved on Ge re-growth. These results are promising for development of high-quality Ge(111) epitaxial layers for photonic and electronic applications.
Morphological fluctuations of individual mitochondria in living cells
Authors: Fernández Casafuz Agustina B , De Rossi María Cecilia , Bruno Luciana
Published: December 2021

Uncovering the link between mitochondrial morphology, dynamics, positioning and function is challenging. Mitochondria are very flexible organelles that are subject to tension and compression within cells. Recent findings highlighted the importance of these mechanical aspects in the regulation of mitochondria dynamics, arising the question on which are the processes and mechanisms involved in their shape remodeling. In this work we explored in detail the morphological changes and spatio-temporal fluctuations of these organelles in living Xenopus laevis melanophores, a well-characterized cellular model. We developed an automatic method for the classification of mitochondria shapes based on the analysis of the curvature of the contour shape from confocal microscopy images. A persistence length of 2.1 μm was measured, quantifying, for the first time, the bending plasticity of mitochondria in their cellular environment. The shape evolution at the single organelle level was followed during a few minutes revealing that mitochondria can bend and unbend in the seconds timescale. Furthermore, the inspection of confocal movies simultaneously registering fluorescent mitochondria and microtubules suggests that the cytoskeleton network architecture and dynamics play a significant role in mitochondria shape remodeling and fluctuations. For instance changes from sinuous to elongated organelles related to transitions from confined behavior to fast directed motion along microtubule tracks were observed.
First demonstration of robust tri-gate β-Ga2O3 nano-membrane field-effect transistors
Authors: Bae Hagyoul , Park Tae Joon , Noh Jinhyun , Chung Wonil , Si Mengwei , Ramanathan Shriram , Ye Peide D
Published: December 2021

Nano-membrane tri-gate β-gallium oxide (β-Ga2O3) field-effect transistors (FETs) on SiO2/Si substrate fabricated via exfoliation have been demonstrated for the first time. By employing electron beam lithography, the minimum-sized features can be defined with the footprint channel width of 50 nm. For high-quality interface between β-Ga2O3 and gate dielectric, atomic layer-deposited 15 nm thick aluminum oxide (Al2O3) was utilized with tri-methyl-aluminum (TMA) self-cleaning surface treatment. The fabricated devices demonstrate extremely low subthreshold slope (SS) of 61 mV dec−1, high drain current (I
DS) ON/OFF ratio of 1.5 × 109, and negligible transfer characteristic hysteresis. We also experimentally demonstrated robustness of these devices with current–voltage (I–V) characteristics measured at temperatures up to 400 °C.
Surface acoustic wave controlled skyrmion-based synapse devices
Authors: Chen Chao , Lin Tao , Niu Jianteng , Sun Yiming , Yang Liu , Kang Wang , Lei Na
Published: December 2021

Magnetic skyrmions, which are particle-like spin structures, are promising information carriers for neuromorphic computing devices due to their topological stability and nanoscale size. In this work, we propose controlling magnetic skyrmions by electric-field-excited surface acoustic waves in neuromorphic computing device structures. Our micromagnetic simulations show that the number of created skyrmions, which emulates the synaptic weight parameter, increases monotonically with increases in the amplitude of the surface acoustic waves. Additionally, the efficiency of skyrmion creation is investigated systemically with a wide range of magnetic parameters, and the optimal values are presented accordingly. Finally, the functionalities of short-term plasticity and long-term potentiation are demonstrated via skyrmion excitation by a sequence of surface acoustic waves with different intervals. The application of surface acoustic waves in skyrmionic neuromorphic computing devices paves a novel approach to low-power computing systems.
Exploring extreme magnetization phenomena in directly driven imploding cylindrical targets
Authors: Walsh C A , Florido R , Bailly-Grandvaux M , Suzuki-Vidal F , Chittenden J P , Crilly A J , Gigosos M A , Mancini R C , Pérez-Callejo G , Vlachos C , McGuffey C , Beg F N , Santos J J
Published: December 2021

This paper uses extended-magnetohydrodynamics (MHD) simulations to explore an extreme magnetized plasma regime realizable by cylindrical implosions on the OMEGA laser facility. This regime is characterized by highly compressed magnetic fields (greater than 10 kT across the fuel), which contain a significant proportion of the implosion energy and induce large electrical currents in the plasma. Parameters governing the different magnetization processes such as Ohmic dissipation and suppression of instabilities by magnetic tension are presented, allowing for optimization of experiments to study specific phenomena. For instance, a dopant added to the target gas-fill can enhance magnetic flux compression while enabling spectroscopic diagnosis of the imploding core. In particular, the use of Ar K-shell spectroscopy is investigated by performing detailed non-LTE atomic kinetics and radiative transfer calculations on the MHD data. Direct measurement of the core electron density and temperature would be possible, allowing for both the impact of magnetization on the final temperature and thermal pressure to be obtained. By assuming the magnetic field is frozen into the plasma motion, which is shown to be a good approximation for highly magnetized implosions, spectroscopic diagnosis could be used to estimate which magnetization processes are ruling the implosion dynamics; for example, a relation is given for inferring whether thermally driven or current-driven transport is dominating.
Compact model of retention characteristics of ferroelectric FinFET synapse with MFIS gate stack
Authors: Baig Md Aftab , Le Hoang-Hiep , De Sourav , Chang Che-Wei , Hsieh Chia-Chi , Huang Xiao-Shan , Lee Yao-Jen , Lu Darsen D
Published: December 2021

In this paper, multiple-fin n- and p-channel HfZrO2 ferroelectric-FinFET devices are manufactured using a gate first process with post metalization annealing. The device transfer characteristics upon program and erase operations are measured and modeled. The drift in the transfer characteristics due to depolarization field and charge injection are captured using the shift in the threshold voltage along with time-dependent modeling of vertical field dependent mobility degradation parameters to develop a physical, computationally efficient, and accurate retention model for ferroelectric-FinFET devices. The modeled conductance is incorporated into deep neural network simulation platform CIMulator to analyze the role of conductance drift due to retention degradation, as well as the importance of the gap between high and low conductance states in improving the image recognition accuracy of neural networks.
Cross correlation mediated by Majorana island with finite charging energy
Authors: Feng Wei , Qin Lupei , Li Xin-Qi
Published: December 2021

Based on the many-particle-number-state treatment for transport through a pair of Majorana zero modes (MZMs) which are coupled to the leads via two quantum dots, we identify that the reason for zero cross correlation of currents at uncoupling limit between the MZMs is from a degeneracy of the teleportation and the Andreev process channels. We then propose a scheme to eliminate the degeneracy by introducing finite charging energy on the Majorana island which allows for coexistence of the two channels. We find nonzero cross correlation established even in the Majorana uncoupling limit (and also in the small charging energy limit), which demonstrates well the teleportation or nonlocal nature of the MZMs. More specifically, the characteristic structure of coherent peaks in the power spectrum of the cross correlation is analyzed to identify the nonlocal and coherent coupling mechanism between the MZMs and the quantum dots. We also display the behaviors of peak shift with variation of the Majorana coupling energy, which can be realized by modulating parameters such as the magnetic field.
Floquet control of indirect exchange interaction in periodically driven two-dimensional electron systems
Authors: Asmar Mahmoud M , Tse Wang-Kong
Published: December 2021

We present a theory for the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction mediated by a two-dimensional (2D) electron system subjected to periodic driving. This is demonstrated for a 2D metal with two ferromagnetic chains deposited in parallel. Our calculations reveal new non-analytic features in the time-averaged spin susceptibility. For weak light–matter coupling, the RKKY interaction shows oscillations with a period tunable by the light amplitude and frequency. For stronger light–matter coupling, the interaction becomes non-oscillatory and remains purely ferromagnetic. Our findings open a path forward for realizing dynamic control of the indirect exchange interaction in 2D magnetic structures.
Study of a MOEMS XOR gate based on optical ring resonator
Authors: Mohammadian Sasan , Babazadeh Farshad , Abedi Kambiz
Published: December 2021

Based on ring resonator with Microelectromechanical systems, optical XOR logic gate is proposed in this paper to realize the optical logic gate application. The proposed gate is basically structured on an optical ring resonator with 7 μm radius and resonance wavelength of 1.55 μm which is placed on the edge of a thin SiC circular diaphragm. In order to apply input voltages to electrodes, two very thin circular gold layers with 50nm air gap spacing are deposited under the diaphragm. Input voltages are considered as logic inputs and resonance wavelength shift as logic output. When an input DC voltage is applied across the diaphragm, an attractive electrostatic force is created between two electrodes. As a result, the diaphragm is deformed and an internal stress is created. This in turn changes the resonator refractive index due to the photoelastic effect and thus shifts its resonance wavelength about 35nm. COMSOL Multiphysics and MATLAB are carried out to verify FEA and numerical analysis of the designed structure, respectively. A good agreement between the simulations and analytical results is obtained. Enhancement of the wavelength shift and FSR are resulted. The proposed structure is used as an optical XOR gate for the first time.
Deuterium retention in W-Ta alloys after low-temperature plasma irradiation and gas exposure
Authors: Bobyr Nikolay P. , Efimov Vitaly S. , Khripunov Boris I. , Kozlov Dmitriy A. , Mednikov Artem A.
Published: December 2021

In this study plates of W, W-xTa alloys (x = 1; 3; 5 concentration in at.%) with a large grain size were used as experimental samples. All the samples were polished to a mirror surface and outgassed in vacuum at 1100 K during 2 h. Sets of W, W-1Ta, W-3Ta, W-5Ta samples were irradiated with low-temperature D plasma up to fluences of 2e25 D m−2. Other sets of W, W-1Ta, W-3Ta, W-5Ta samples were exposed in D2 gas in a temperature range of 425 ÷ 625 K and pressure 103 Pa. The D retention in W and W-Ta alloys was measured by thermal desorption spectroscopy (TDS). An influence of Ta dopant on deuterium retention in W was observed. The dopant of tantalum slightly reduces the accumulation of deuterium in tungsten during gas exposure. Increasing temperature of samples during D-plasma irradiation from 415 K to 615 K reduces deuterium retention up to 2 orders of magnitude.
Non-locality and geometric potential provide the phenomenology of the double-hole single massive particle and light interference
Authors: Castañeda Román , Bedoya Pablo , Matteucci Giorgio
Published: December 2021

In spite of its accurate prediction of the experimental outcomes of double-hole single particle interference, quantum mechanics does not provide a phenomenological description of the individual realizations of the experiment. By defining a non-locality function and considering the non-paraxial solution of the time-independent Schrödinger equation by the Green’s theorem, we introduce a geometrical potential which leads to an outstanding result. The geometric potential allows the description of spatially structured Lorentzian wells in the volume between the double-hole mask and the detector. The buildup of the interference patterns results from the confined propagation of single particles through these Lorentzian wells. The phenomenological implications of this description are discussed and illustrated by numerical examples, and its compatibility with quantum mechanical predictions is also shown. A further, non-trivial advantage of this model over the conventional formalism, is that the present quantum probability density can be exactly calculated both in the near and far field conditions.
Reducing reflectivity of stimulated Raman scattering by discretely changing phase of incident light in inertial fusion plasmas
Authors: Yang T , Zhang S T , Zhou Y Z , Liu D J , Li X M , Liu Z J , Cao L H , Zheng C Y , He X T
Published: December 2021

A new method to reduce the stimulated Raman scattering (SRS) in inertial confinement fusion conditions is proposed by changing the incident light phase discretely. The proposal is first examined by three-wave coupling equations and then verified by Vlasov simulations. A remarkable decreasing in SRS reflectivity is observed when the period of phase changing is less than

2
π
/
γ
,

where

γ

is the growth rate of SRS. By contrast, some simulations with continuously changing phase of incident light are carried out to compare their influence on SRS. In addition, the proposal may suppress the stimulated Brillouin scattering.
Lagrangian approach to super-sample effects on biased tracers at field level: galaxy density fields and intrinsic alignments
Authors: Taruya Atsushi , Akitsu Kazuyuki
Published: December 2021

It has been recognized that the observables of large-scale structure (LSS) is susceptible to long-wavelength density and tidal fluctuations whose wavelengths exceed the accessible scale of a finite-volume observation, referred to as the super-sample modes. The super-sample modes modulate the growth and expansion rate of local structures, thus affecting the cosmological information encoded in the statistics of galaxy clustering data. In this paper, based on the Lagrangian perturbation theory, we develop a new formalism to systematically compute the response of a biased tracer of LSS, which is expressed perturbatively in terms of the matter density field of sub-survey modes, to the super-sample modes at the field level. The formalism presented here reproduces the power spectrum responses that have been previously derived, and provides an alternative way to compute statistical quantities with super-sample modes.
As an application, we consider the statistics of the intrinsic alignments of galaxies and halos, and derive the field response of the galaxy/halo shape bias to the super-sample modes. Possible impacts of the long-mode contributions on the covariance of the three-dimensional power spectra of the intrinsic alignment are also discussed, and the signal-to-noise ratios are estimated.
Zoology of graviton non-Gaussianities
Authors: Cabass Giovanni
Published: December 2021

We characterize graviton non-Gaussianities in models of inflation where de Sitter
boosts are spontaneously broken. We discuss which of the symmetry breaking patterns studied in Nicolis et al., 2015 [1] can sustain a period of quasi de Sitter expansion, and show that the
symmetry breaking pattern of Solid Inflation allows the most freedom for graviton interactions.
We comment on the phenomenological consequences of some of these interactions. As a byproduct of
this analysis we construct the “EFT of Solid Inflation”, which has all the useful features
of the EFT of Inflation but for the case of broken spatial diffeomorphisms.
Anti-symmetric clustering signals in the observed power spectrum
Authors: Fonseca José , Clarkson Chris
Published: December 2021

In this paper, we study how to directly measure the effect of peculiar velocities in the observed angular power spectra. We do this by constructing a new anti-symmetric estimator of Large Scale Structure using different dark matter tracers. We show that the Doppler term is the major component of our estimator and we show that we can measure it with a signal-to-noise ratio up to ∼ 50 using a futuristic SKAO HI galaxy survey. We demonstrate the utility of this estimator by using it to provide constraints on the Euler equation.
Local stability analysis of a low-dissipation cyclic refrigerator
*
Authors: Li Kai , Lin Jie , Wang Jian-Hui
Published: December 2021

We study the local stability near the maximum figure of merit for the low-dissipation cyclic refrigerator, where the irreversible dissipation occurs not only in the thermal contacts but also the adiabatic strokes. We find that the bounds of the coefficient of performance at a maximum figure of merit or maximum cooling rate in the presence of internal dissipation are identical to those in the corresponding absence of internal dissipation. Using two different scenarios, we prove the existence of a single stable steady state for the refrigerator, and clarify the role of internal dissipation on the stability of the thermodynamic steady state, showing that the speed of system evolution to the steady state decreases due to internal dissipation.
Nonlinear inversion of ultrasonic guided waves for in vivo evaluation of cortical bone properties
Authors: Song Xiaojun , Fan Tiandi , Zeng Jundong , Shi Qin-Zhen , Huang Qiong , Gu Meilin , Moilanen Petro , Li Yi-Fang , Ta Dean
Published: December 2021

Ultrasonic guided waves (UGWs), which propagate throughout the entire thickness of cortical bone, are attractive for the early diagnosis of osteoporosis. However, this is challenging due to the impact of soft tissue and the inherent difficulties related to multiparametric inversion of cortical bone quality factors, such as cortical thickness and bulk wave velocity. Therefore, in this research, a UGW-based multi-parameter inversion algorithm is developed to predict strength-related factors. In simulation, a free plate (cortical bone) and a bilayer plate (soft tissue and cortical bone) are used to validate the proposed method. The inversed cortical thickness (CTh), longitudinal velocity (V
L) and transverse velocity (V
T) are in accordance with the true values. Then four bovine cortical bone plates were used in in vitro experiments. Compared with the reference values, the relative errors for cortical thickness were 3.96%, 0.83%, 2.87%, and 4.25%, respectively. In the in vivo measurements, UGWs are collected from the tibias of 10 volunteers. The theoretical dispersion curves depicted by the estimated parameters (V
T, V
L, CTh) match well with the extracted experimental ones. In comparison with dual-energy x-ray absorptiometry, our results show that the estimated transverse velocity and cortical thickness are highly sensitive to osteoporosis. Therefore, these two parameters (CTh and V
T) of long bones have potential to be used for diagnosis of bone status in clinical applications.
Topological Lifshitz transition and novel edge states induced by non-Abelian SU(2) gauge field on bilayer honeycomb lattice
Authors: Guo Wen-Xiang , Liu Wu-Ming
Published: December 2021

We investigate the SU(2) gauge effects on bilayer honeycomb lattice thoroughly. We discover a topological Lifshitz transition induced by the non-Abelian gauge potential. Topological Lifshitz transitions are determined by topologies of Fermi surfaces in the momentum space. Fermi surface consists of N = 8 Dirac points at π-flux point instead of N = 4 in the trivial Abelian regimes. A local winding number is defined to classify the universality class of the gapless excitations. We also obtain the phase diagram of gauge fluxes by solving the secular equation. Furthermore, the novel edge states of biased bilayer nanoribbon with gauge fluxes are also investigated.
Fabrication and investigation of ferroelectric memristors with various synaptic plasticities
Authors: Qin Qi , Zhang Miaocheng , Yao Suhao , Chen Xingyu , Han Aoze , Chen Ziyang , Ma Chenxi , Wang Min , Chen Xintong , Wang Yu , Zhang Qiangqiang , Liu Xiaoyan , Hu Ertao , Wang Lei , Tong Yi
Published: December 2021

In the post-Moore era, neuromorphic computing has been mainly focused on breaking the von Neumann bottlenecks. Memristors have been proposed as a key part of neuromorphic computing architectures, and can be used to emulate the synaptic plasticities of the human brain. Ferroelectric memristors represent a breakthrough for memristive devices on account of their reliable nonvolatile storage, low write/read latency and tunable conductive states. However, among the reported ferroelectric memristors, the mechanisms of resistive switching are still under debate. In addition, there needs to be more research on emulation of the brain synapses using ferroelectric memristors. Herein, Cu/PbZr0.52Ti0.48O3 (PZT)/Pt ferroelectric memristors have been fabricated. The devices are able to realize the transformation from threshold switching behavior to resistive switching behavior. The synaptic plasticities, including excitatory post-synaptic current, paired-pulse facilitation, paired-pulse depression and spike time-dependent plasticity, have been mimicked by the PZT devices. Furthermore, the mechanisms of PZT devices have been investigated by first-principles calculations based on the interface barrier and conductive filament models. This work may contribute to the application of ferroelectric memristors in neuromorphic computing systems.
Gaussianization of peculiar velocities and bulk flow measurement
Authors: Qin Fei
Published: December 2021

The line-of-sight peculiar velocities are good indicators of the gravitational fluctuation of the density field. Techniques have been developed to extract cosmological information from the peculiar velocities in order to test cosmological models. These techniques include measuring cosmic flow, measuring two-point correlation and power spectrum of the peculiar velocity fields, and reconstructing the density field using peculiar velocities. However, some measurements from these techniques are biased due to the non-Gaussianity of the estimated peculiar velocities. Therefore, we rely on the 2MTF survey to explore a power transform that can Gaussianize the estimated peculiar velocities. We find a tight linear relation between the transformation parameters and the measurement errors of log-distance ratio. To show an example for the implementation of Gaussianized peculiar velocities in cosmology, we develop a bulk flow estimator and estimate bulk flow from the Gaussianized peculiar velocities. We use 2MTF mocks to test the algorithm, and we find the algorithm yields unbiased measurements. We also find this technique gives smaller measurement errors compared to other techniques. In Galactic coordinates, at the depth of 30h−1Mpc, we measure a bulk flow of 332 ± 27 km s−1in the direction (l,b) = (293° ± 5°, 13° ± 4°). The measurement is consistent with the ΛCDM prediction.
The low cosmic-ray density in the Polaris Flare
Authors: Cui Zhi-Wei , Yang Rui-Zhi , Liu Bing
Published: December 2021

We reported the γ-ray observation towards the giant molecular cloud Polaris Flare. Together with the dust column density map, we derived the cosmic ray (CR) density and spectrum in this cloud. Compared with the CR measured locally, the CR density in the Polaris Flare is significantly lower and the spectrum is softer. Such a different CR spectrum reveals either a rather large gradient of CR distribution in the direction perpendicular to the Galactic plane or a suppression of CR inside molecular clouds.
Weak lensing magnification reconstruction with the modified internal linear combination method
Authors: Hou Shu-Tong , Yu Yu , Zhang Peng-Jie
Published: December 2021

Measuring weak lensing cosmic magnification signal is very challenging due to the overwhelming intrinsic clustering in the observed galaxy distribution. In this paper, we modify the Internal Linear Combination (ILC) method to reconstruct the lensing signal with an extra constraint to suppress the intrinsic clustering. To quantify the performance, we construct a realistic galaxy catalogue for the LSST-like photometric survey, covering 20 000 deg2 with mean source redshift at zs
∼ 1. We find that the reconstruction performance depends on the width of the photo-z bin we choose. Due to the correlation between the lensing signal and the source galaxy distribution, the derived signal has smaller systematic bias but larger statistical uncertainty for a narrower photo-z bin. We conclude that the lensing signal reconstruction with the Modified ILC method is unbiased with a statistical uncertainty <5% for bin width Δ zP
= 0.2.
Intra-day variability of BL Lacertae from 2016 to 2018
Authors: Li Tian , Wu Jiang-Hua , Meng Nan-Kun , Dai Yan , Zhang Xiao-Yuan
Published: December 2021

We monitored BL Lacertae in the B, V, R and I bands for 14 nights during the period of 2016–2018. The source showed significant intra-day variability on 12 nights. We performed color-magnitude analysis and found that the source exhibited bluer-when-brighter chromatism. This bluer-when-brighter behavior is at least partly caused by the larger variation amplitude at shorter wavelengths. The variations at different wavelengths are correlated well and show no inter-band time lag.
Spectral energy distribution similarity of the local galaxies and the 3.6 μm selected galaxies from the Spitzer Extended Deep Survey
Authors: Cheng Cheng , Huang Jia-Sheng , Xu Hai , Jin Gao-Xiang , He Chuan , Cao Tian-Wen , Li Zi-Jian , Wu Shu-Mei , Liang Piao-Ran , Shi Ya-Ru , Shao Xu , Dai Y. Sophia , Xu Cong Kevin , Musin Marat
Published: December 2021

The Spitzer Extended Deep Survey (SEDS) as a deep and wide mid-infrared (MIR) survey project provides a sample of 500 000+ sources spreading 1.46 square degree and a depth of 26 AB mag (3σ). Combining with the previous available data, we build a PSF-matched multi-wavelength photometry catalog from u band to 8 μm. We fit the SEDS galaxies spectral energy distributions by the local galaxy templates. The results show that the SEDS galaxy can be fitted well, indicating the high redshift galaxy (z ∼ 1) shares the same templates with the local galaxies. This study would facilitate the further study of the galaxy luminosity and high redshift mass function.
New constraint of the Hubble constant by proper motions of radio components observed in AGN twin-jets
Authors: Lu Wei-Jian , Qin Yi-Ping
Published: December 2021

As the advent of precision cosmology, the Hubble constant (H
0) inferred from the Lambda Cold Dark Matter fit to the Cosmic Microwave Background data is increasingly in tension with the measurements from the local distance ladder. To approach its real value, we need more independent methods to measure, or to make constraint of, the Hubble constant. In this paper, we apply a plain method, which is merely based on the Friedman-Lemaître-Robertson-Walker cosmology together with geometrical relations, to constrain the Hubble constant by proper motions of radio components observed in AGN twin-jets. Under the assumption that the ultimate ejection strengths in both sides of the twin-jet concerned are intrinsically the same, we obtain a lower limit of H
0,min = 51.5 ± 2.3 km s−1 Mpc−1 from the measured maximum proper motions of the radio components observed in the twin-jet of NGC 1052.
Evaluation of hadronic emission in starburst galaxies and star-forming galaxies
Authors: Xiang Yun-Chuan , Jiang Ze-Jun , Tang Yun-Yong
Published: December 2021

In this work, we reanalyzed 11 years of spectral data from the Fermi Large Area Telescope (Fermi-LAT) of currently observed starburst galaxies (SBGs) and star-forming galaxies (SFGs). We used a one-zone model provided by NAIMA and the hadronic origin to explain the GeV observation data of the SBGs and SFGs. We found that a protonic distribution of a power-law form with an exponential cutoff can explain the spectra of most SBGs and SFGs. However, it cannot explain the spectral hardening components of NGC 1068 and NGC 4945 in the GeV energy band. Therefore, we considered the two-zone model to well explain these phenomena. We summarized the features of two model parameters, including the spectral index, cutoff energy, and proton energy budget. Similar to the evolution of supernova remnants (SNRs) in the Milky Way, we estimated the protonic acceleration limitation inside the SBGs to be the order of 102 TeV using the one-zone model; this is close to those of SNRs in the Milky Way.
Subcritical dynamo and hysteresis in a Babcock-Leighton type kinematic dynamo model
Authors: Vashishth Vindya , Karak Bidya Binay , Kitchatinov Leonid
Published: December 2021

In the Sun and Sun-like stars, it is believed that cycles of the large-scale magnetic field are produced due to the existence of differential rotation and helicity in the plasma flows in their convection zones (CZs). Hence, it is expected that for each star, there is a critical dynamo number for the operation of a large-scale dynamo. As a star slows down, it is expected that the large-scale dynamo ceases to operate above a critical rotation period. In our study, we explore the possibility of the operation of the dynamo in the subcritical region using the Babcock–Leighton type kinematic dynamo model. In some parameter regimes, we find that the dynamo shows hysteresis behavior, i.e., two dynamo solutions are possible depending on the initial parameters—decaying solution if starting with weak field and strong oscillatory solution (subcritical dynamo) when starting with a strong field. However, under large fluctuations in the dynamo parameter, the subcritical dynamo mode is unstable in some parameter regimes. Therefore, our study supports the possible existence of subcritical dynamo in some stars which was previously demonstrated in a mean-field dynamo model with distributed α and MHD turbulent dynamo simulations.
Research on performances of back-illuminated scientific CMOS for astronomical observations
Authors: Qiu Peng , Zhao Yong , Zheng Jie , Wang Jian-Feng , Jiang Xiao-Jun
Published: December 2021

To evaluate performances of a back-illuminated scientific CMOS (sCMOS) camera for astronomical observations, comparison tests between Andor Marana sCMOS and Andor iKon-L 936 CCD cameras were conducted in a laboratory and on a telescope. The laboratory tests showed that the readout noise of the sCMOS camera is about half lower, the dark current is about 17 times higher, the dynamic range is lower in the 12-bit setting and higher in the 16-bit setting, and the linearity and bias stability are comparable relative to those of the CCD camera. In field tests, we observed the open cluster M67 with the sCMOS and CCD cameras on a 60 cm telescope. Unlike the CCD camera, the sCMOS camera has a dual-amplifier architecture. Since a 16-bit image of the sCMOS camera is composed of two 12-bit images sampled with 12-bit high gain and low gain amplifiers simultaneously, it is not real 16-bit output data. The evaluation tests indicated that the dual-amplifier architecture of the sCMOS camera leads to a decline of photometric stability by about six times around specific pixel counts. For photometry of bright objects with similar magnitudes that require high frame rates, the sCMOS camera under 12-bit setting is a good choice. Therefore, the sCMOS camera is fitted with survey observations of variable objects requiring short exposure times, mostly less than 1 s, and high frame rates. It also satisfies the requirements for an offset guiding instrument owing to its high sensitivity, high temporal resolution and high stability.