Subjects -> ASTRONOMY (Total: 94 journals)
 Showing 1 - 46 of 46 Journals sorted alphabetically Advances in Astronomy       (Followers: 49) Annual Review of Astronomy and Astrophysics       (Followers: 50) Annual Review of Earth and Planetary Sciences       (Followers: 67) Artificial Satellites       (Followers: 21) Astrobiology       (Followers: 11) Astronomical & Astrophysical Transactions: The Journal of the Eurasian Astronomical Society       (Followers: 7) Astronomical Review       (Followers: 5) Astronomische Nachrichten       (Followers: 4) Astronomy & Geophysics       (Followers: 49) Astronomy and Astrophysics       (Followers: 67) Astronomy and Computing       (Followers: 6) Astronomy Letters       (Followers: 22) Astronomy Reports       (Followers: 22) Astronomy Studies Development       (Followers: 15) Astroparticle Physics       (Followers: 10) Astrophysical Bulletin       (Followers: 4) Astrophysics       (Followers: 35) Astrophysics and Space Science       (Followers: 49) Astrophysics and Space Sciences Transactions (ASTRA)       (Followers: 60) Astropolitics: The International Journal of Space Politics & Policy       (Followers: 13) Celestial Mechanics and Dynamical Astronomy       (Followers: 15) Chinese Astronomy and Astrophysics       (Followers: 25) Colloid Journal       (Followers: 2) Comptes Rendus : Physique       (Followers: 2) Computational Astrophysics and Cosmology       (Followers: 6) Earth and Planetary Science Letters       (Followers: 143) Earth, Moon, and Planets       (Followers: 47) Earth, Planets and Space       (Followers: 77) EAS Publications Series       (Followers: 8) EPL Europhysics Letters       (Followers: 8) Experimental Astronomy       (Followers: 38) Expert Opinion on Astronomy and Astrophysics       (Followers: 8) Extreme Life, Biospeology & Astrobiology - International Journal of the Bioflux Society       (Followers: 4) Few-Body Systems       (Followers: 1) Foundations of Physics       (Followers: 40) Frontiers in Astronomy and Space Sciences       (Followers: 15) Galaxies       (Followers: 6) Globe, The       (Followers: 3) Gravitation and Cosmology       (Followers: 6) Icarus       (Followers: 71) International Journal of Advanced Astronomy       (Followers: 21) International Journal of Astrobiology       (Followers: 4) International Journal of Astronomy       (Followers: 22) International Journal of Astronomy and Astrophysics       (Followers: 36) International Journal of Satellite Communications Policy and Management       (Followers: 15) International Letters of Chemistry, Physics and Astronomy       (Followers: 8) ISRN Astronomy and Astrophysics       (Followers: 14) Journal for the History of Astronomy       (Followers: 20) Journal of Astrobiology & Outreach       (Followers: 5) Journal of Astronomical Instrumentation       (Followers: 3) Journal of Astrophysics       (Followers: 33) Journal of Astrophysics and Astronomy       (Followers: 58) Journal of Atmospheric and Solar-Terrestrial Physics       (Followers: 133) Journal of Geophysical Research : Planets       (Followers: 116) Journal of Geophysical Research : Space Physics       (Followers: 136) Journal of High Energy Astrophysics       (Followers: 25) Kinematics and Physics of Celestial Bodies       (Followers: 11) KronoScope       (Followers: 1) Macalester Journal of Physics and Astronomy       (Followers: 5) Monthly Notices of the Royal Astronomical Society       (Followers: 13) Monthly Notices of the Royal Astronomical Society : Letters       (Followers: 2) Nature Astronomy       (Followers: 14) New Astronomy       (Followers: 26) New Astronomy Reviews       (Followers: 19) Nonlinear Dynamics       (Followers: 19) NRIAG Journal of Astronomy and Geophysics       (Followers: 4) Physics of the Dark Universe       (Followers: 4) Planetary and Space Science       (Followers: 106) Planetary Science       (Followers: 52) Proceedings of the International Astronomical Union       (Followers: 2) Publications of the Astronomical Society of Australia       (Followers: 3) Publications of the Astronomical Society of Japan       (Followers: 4) Research & Reviews : Journal of Space Science & Technology       (Followers: 20) Research in Astronomy and Astrophysics       (Followers: 38) Revista Mexicana de Astronomía y Astrofísica       (Followers: 3) Science China : Physics, Mechanics & Astronomy       (Followers: 4) Science China Physics, Mechanics & Astronomy       (Followers: 4) Solar Physics       (Followers: 29) Solar System Research       (Followers: 15) Space Science International       (Followers: 118) Space Science Reviews       (Followers: 92) Space Weather       (Followers: 27) Transport and Aerospace Engineering       (Followers: 13) Universe       (Followers: 6)
Similar Journals
 Science China Physics, Mechanics & AstronomyJournal Prestige (SJR): 0.488 Citation Impact (citeScore): 2Number of Followers: 4      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1674-7348 - ISSN (Online) 1869-1927 Published by Springer-Verlag  [2469 journals]
• Interpretation of the η1 (1855) as a KK̄1(1400) + c.c. molecule

Abstract: Abstract An exotic state with JPC = 1−+, denoted by η1(1855), was observed by BESIII Collaboration recently in J/ψ → γηη′. The fact that its mass is just below the threshold of KK̄1(1400) stimulates us to investigate whether this exotic state can be interpreted as a KK̄1(1400) + c.c. molecule or not. Using the one boson exchange model, we show that it is possible for KK̄1(1400) with JPC = 1−+ to bind together by taking the momentum cutoff Λ ≳ 2 GeV and yield the same binding energy as the experimental value when Λ ≈ 2.5 GeV. In this molecular picture, the predicted branch ratio Br(η1(1855) → ηη′) ≈ 15% is consistent with the experimental results, which again supports the molecular explanation of η1(1855). Relevant systems, namely KK̄1(1400) with JPC = 1−− and KK̄1(1270) with JPC = 1−±, are also investigated, some of which can be searched for in the future experiments.
PubDate: 2022-05-05

• Modeling the arc and ring structures in the HD 143006 disk

Abstract: Abstract Rings and asymmetries in protoplanetary disks are considered as signposts of ongoing planet formation. In this work, we conduct three-dimensional radiative transfer simulations to model the intriguing disk around HD 143006 that has three dust rings and a bright arc. A complex geometric configuration, with a misaligned inner disk, is assumed to account for the asymmetric structures. The two-dimensional surface density is constructed by iteratively fitting the ALMA data. We find that the dust temperature displays a notable discontinuity at the boundary of the misalignment. The ring masses range from 0.6 to 16 M⊕ that are systematically lower than those inferred in the younger HL Tau disk. The arc occupies nearly 20% of the total dust mass. Such a high mass fraction of dust grains concentrated in a local region is consistent with the mechanism of dust trapping into vortices. Assuming a gas-to-dust mass ratio of 30 that is constant throughout the disk, the dense and cold arc is close to the threshold of being gravitationally unstable, with the Toomre parameter Q ∼ 1.3. Nevertheless, our estimate of Q relies on the assumption for the unknown gas-to-dust mass ratio. Adopting a lower gas-to-dust mass ratio would increase the inferred Q value. Follow-up high resolution observations of dust and gas lines are needed to clarify the origin of the substructures.
PubDate: 2022-05-05

• Search for gamma-ray line signals around the black hole at the galactic
center with DAMPE observation

Abstract: Abstract The adiabatic growth of a black hole (BH) may enhance the dark matter (DM) density surrounding it, causing a spike in the DM density profile. The spike around the supermassive BH at the center of the Milky Way may lead to a dramatic enhancement of the gamma-ray flux of DM annihilation from the galactic center (GC). In this work, we analyze the gamma-ray data of the innermost region (i.e., the inner 1°) of the GC to search for potential line-like signals from the BH spike. Such line-like signals could be generated in the process of DM particles annihilating into double photons. We adopt the gamma-ray data from the Dark Matter Particle Explorer (DAMPE). Although the DAMPE has a much smaller effective area than the Fermi-LAT, the gamma-ray line search can benefit from its unprecedented high energy resolution. No significant line-like signals are found in our analysis. We derive upper limits on the cross section of the annihilation based on this non-detection. We find that despite the DAMPE’s small effective area for photon detection, we can still place strong constraints on the cross section (〈σν〉 ≲ 10−27 cm3 s−1) in the spike scenario due to the very bright model-expected flux from the spike. Our results indicate that either DM does not annihilate primarily through the γγ channel in the mass range we considered or no sharp density spike is present at the GC.
PubDate: 2022-05-05

• Ambi-chiral anomalous Hall effect in magnetically doped topological
insulators

Abstract: Abstract The chirality associated with broken time-reversal symmetry in magnetically doped topological insulators has important implications for the quantum transport phenomena. Here we report anomalous Hall effect studies in Mn- and Cr-doped Bi2Te3 topological insulators with varied thicknesses and doping contents. By tracing the magnitude of the anomalous Hall resistivity, we find that the Mn-type anomalous Hall effect characterized with clockwise chirality is strengthened by the reduction of film thickness, which is opposite to that of the Cr-type anomalous Hall effect with counterclockwise chirality. We provide a phenomenological physical picture to explain the evolution of the magnetic order and the anomalous Hall chirality in magnetically doped topological insulators.
PubDate: 2022-04-29

• Correlation-enhanced electron-phonon coupling for accurate evaluation of
the superconducting transition temperature in bulk FeSe

Abstract: Abstract It has been widely recognized that, based on standard density functional theory calculations of the electron-phonon coupling, the superconducting transition temperature (Tc) in bulk FeSe is exceptionally low (almost 0 K) within the Bardeen-Cooper-Schrieffer formalism. Yet the experimentally observed Tc is much higher (∼10 K), and the underlying physical origin remains to be fully explored, especially at the quantitative level. Here we present the first accurate determination of Tc in FeSe where the correlation-enhanced electron-phonon coupling is treated within first-principles dynamical mean-field theory. Our studies treat both the multiple electronic bands across the Fermi level and phononic bands, and reveal that all the optical phonon modes are effectively coupled with the conduction electrons, including the important contributions of a single breathing mode as established by previous experiments. Accordingly, each of those phonon modes contributes pronouncedly to the electron pairing, and the resultant Tc is drastically enhanced to the experimentally observed range. The approach developed here should be broadly applicable to other superconducting systems where correlation-enhanced electron-phonon coupling plays an important role.
PubDate: 2022-04-29

• Unraveling the threshold stress of structural rejuvenation of metallic
glasses via thermo-mechanical creep

Abstract: Abstract The competition between physical aging and structural rejuvenation determines the physical and mechanical properties of glassy materials. Thus, the rejuvenation-aging boundary must be identified quantitatively. In this work, we unravel a stress boundary to distinguish rejuvenation from aging via the thermo-mechanical creep of a typical Zr-based metallic glass. The crept glasses were rejuvenated into high-enthalpy disordered states when the applied stress exceeded a threshold that was numerically close to the steady-state flow stress; otherwise, the glasses were aged. A theoretical model for glass creep was adopted to demystify the observed stress threshold of rejuvenation. The model revealed that the thermo-mechanical creep beyond the threshold stress could activate sufficient shear transformations to create a net free volume, thus leading to structural rejuvenation. Furthermore, we derived the analytical expressions for the threshold and flow stresses. Both stresses can act as the rejuvenation-aging boundary, which is well supported by experimental creep data. The present work procures a deeper understanding of the rejuvenation mechanism of glasses and provides useful implications for abstaining from glass aging.
PubDate: 2022-04-29

• A numerical method to predict the membrane tension distribution of

Abstract: Abstract Changes in membrane tension significantly affect the physiological functions of cells in various ways. However, directly measuring the spatial distribution of membrane tension remains an ongoing issue. In this study, an algorithm is proposed to determine the membrane tension inversely by executing a particle-based method and searching for the minimum deformation energy based on the cell images and focal adhesions. A standard spreading cell model is established using 3D reconstructions with images from structured illumination microscopy as the reference cell shape. The membrane tension distribution, forces across focal adhesions, and profile of the spread cell are obtained using this method, until the cell deformation energy function optimization converges. Qualitative and quantitative comparisons with previous experimental results validated the reliability of this method. The results show that in the standard spreading cell model, the membrane tension decreases from the bottom to the top of the membrane. This method can be applied to predict the membrane tension distribution of cells freely spreading into different shapes, which could improve the quantitative analysis of cellular membrane tension in various studies for cell mechanics.
PubDate: 2022-04-26

• Limits on sequential sharing of nonlocal advantage of quantum coherence

Abstract: Abstract Sequential sharing of nonlocal correlation is inherently related to its application. We address the question as to how many observers can share the nonlocal advantage of quantum coherence (NAQC) in a (d × d)-dimensional state, where d is a prime or a power of a prime. We first analyze the trade-off between disturbance and information gain of the general d-dimensional unsharp measurements. Then in a scenario where multiple Alices perform unsharp measurements on one party of the state sequentially and independently and a single Bob measures coherence of the conditional states on the other party, we show that at most one Alice can demonstrate NAQC with Bob. This limit holds even when considering the weak measurements with optimal pointer states. These results may shed light on the interplay between nonlocal correlations and quantum measurements on high-dimensional systems and the hierarchy of different quantum correlations.
PubDate: 2022-04-26

• Self-consistent effective-one-body theory for spinless binaries based on
post-Minkowskian approximation I: Hamiltonian and decoupled equation for
$$\psi _4^{\rm{B}}$$ ψ 4 B

Abstract: Abstract To build a self-consistent effective-one-body (EOB) theory, in which the Hamiltonian, radiation-reaction force and waveform for the “plus” and “cross” modes of the gravitational wave should be based on the same effective background spacetime, the key step is to look for the decoupled equation for $$\psi _4^{\rm{B}} = {\ddot h_ +} - {\rm{i}}{\ddot h_ \times}$$ , which seems a very difficult task because there are non-vanishing tetrad components of the tracefree Ricci tensor for such spacetime. Fortunately, based on an effective spacetime obtained in this paper by using the post-Minkowskian (PM) approximation, we find the decoupled equation for $$\psi _4^{\rm{B}}$$ by dividing the perturbation part of the metric into the odd and even parities. With the effective metric and decoupled equation at hand, we set up a frame of self-consistent EOB model for spinless binaries.
PubDate: 2022-04-26

• A semiclassical approach to surface Fermi arcs in Weyl semimetals

Abstract: Abstract We present a semiclassical explanation for the morphology of the surface Fermi arcs of Weyl semimetals. Viewing the surface states as a two-dimensional Fermi gas subject to band bending and Berry curvatures, we show that it is the non-parallelism between the velocity and the momentum that gives rise to the spiral structure of Fermi arcs. We map out the Fermi arcs from the velocity field for a single Weyl point and a lattice with two Weyl points. We also investigate the surface magnetoplasma of Dirac semimetals in a magnetic field, and find that the drift motion, the chiral magnetic effect and the Imbert-Fedorov shift are all involved in the formation of surface Fermi arcs. Our work not only provides an insightful perspective on the surface Fermi arcs and a practical way to find the surface dispersion, but also paves the way for the study of other physical properties of the surface states of topological semimetals, such as transport properties and orbital magnetization, using semiclassical methods.
PubDate: 2022-04-26

• Molecular transport under extreme confinement

Abstract: Abstract Mass transport through the nanoporous medium is ubiquitous in nature and industry. Unlike the macroscale transport phenomena which have been well understood by the theory of continuum mechanics, the relevant physics and mechanics on the nanoscale transport still remain mysterious. Recent developments in fabrication of slit-like nanocapillaries with precise dimensions and atomically smooth surfaces have promoted the fundamental research on the molecular transport under extreme confinement. In this review, we summarized the contemporary progress in the study of confined molecular transport of water, ions and gases, based on both experiments and molecular dynamics simulations. The liquid exhibits a pronounced layered structure that extends over several intermolecular distances from the solid surface, which has a substantial influence on static properties and transport behaviors under confinement. Latest studies have also shown that those molecular details could provide some new understanding on the century-old classical theory in this field.
PubDate: 2022-04-25

• Dissipation-induced nonreciprocal magnon blockade in a magnon-based hybrid
system

Abstract: Abstract We propose an experimentally realizable nonreciprocal magnonic device at the single-magnon level by exploiting magnon blockade in a magnon-based hybrid system. The coherent qubit-magnon coupling, mediated by virtual photons in a microwave cavity, leads to the energy-level anharmonicity of the composite modes. In contrast, the corresponding dissipative counterpart, induced by traveling microwaves in a waveguide, yields inhomogeneous broadenings of the energy levels. As a result, the cooperative effects of these two kinds of interactions give rise to the emergence of the direction-dependent magnon blockade. We show that this can be demonstrated by studying the equal-time second-order correlation function of the magnon mode. Our study opens an avenue to engineer nonreciprocal magnonic devices in the quantum regime involving only a small number of magnons.
PubDate: 2022-04-19

• Extracting governing system for the plastic deformation of metallic
glasses using machine learning

Abstract: Abstract This paper shows hidden information from the plastic deformation of metallic glasses using machine learning. Ni62Nb38 (at.%) metallic glass (MG) film and Zr64.13Cu15.75Al10Ni10.12 (at.%) BMG, as two model materials, are considered for nano-scratching and compression experiment, respectively. The interconnectedness among variables is probed using correlation analysis. The evolvement mechanism and governing system of plastic deformation are explored by combining dynamical neural networks and sparse identification. The governing system has the same basis function for different experiments, and the coefficient error is ≤ 0.14% under repeated experiments, revealing the intrinsic quality in metallic glasses. Furthermore, the governing system is conducted based on the preceding result to predict the deformation behavior. This shows that the prediction agrees well with the real value for the deformation process.
PubDate: 2022-04-18

• Investigation of the effect of quantum measurement on parity-time symmetry

Abstract: Abstract Symmetry, including the parity-time (PT)-symmetry, is a striking topic, widely discussed and employed in many fields. It is well-known that quantum measurement can destroy or disturb quantum systems. However, can and how does quantum measurement destroy the symmetry of the measured system' To answer the pertinent question, we establish the correlation between the quantum measurement and Floquet PT-symmetry and investigate for the first time how the measurement frequency and measurement strength affect the PT-symmetry of the measured system using the 40Ca+ ion. It is already shown that the measurement at high frequencies would break the PT symmetry. Notably, even for an inadequately fast measurement frequency, if the measurement strength is sufficiently strong, the PT symmetry breaking can occur. The current work can enhance our knowledge of quantum measurement and symmetry and may inspire further research on the effect of quantum measurement on symmetry.
PubDate: 2022-04-15

• Stability of superconducting Nd0.8Sr0.2NiO2 thin films

Abstract: Abstract The discovery of superconducting states in the nickelate thin film with infinite-layer structure has paved a new way for studying unconventional superconductivity. So far, research in this field is still very limited due to difficulties in sample preparation. Here we report the successful preparation of the superconducting state of Nd0.8Sr0.2NiO2 thin film (Tc = 8.0–11.1 K) and study the stability of such films in the ambient environment, water, and under electrochemical conditions. Our work demonstrates that the superconducting state of Nd0.8Sr0.2NiO2 is remarkably stable, which can last for at least 47-day continuous exposure to air at 20°C and 35% relative humidity. We also show that the superconductivity disappears after being immersed in de-ionized water at room temperature for 5 h. Surprisingly, it can also survive under ionic liquid gating conditions with an applied voltage of about 4 V, which is even more stable than conventional perovskite complex oxides.
PubDate: 2022-04-14

• Freezing crystallographic defects into nanoparticles: The development of
pulsed laser defect engineering in liquid (PUDEL)

PubDate: 2022-04-11

• Generation of nanomaterials by reactive laser-synthesis in liquid

Abstract: Abstract Nanomaterials with tailored structures and surface chemistry are in high demand, as these materials play increasingly important roles in biology, catalysis, energy storage, and manufacturing. Their heightened demand has attracted attention towards the development of synthesis routes, particularly, laser-synthesis techniques. These efforts drove the refinement of laser ablation in liquid (LAL) and related methods over the past two decades and have led to the emergence of reactive laser-synthesis techniques that exploit these methods’ characteristic, non-equilibrium conditions. Reactive laser-synthesis approaches foster unique chemical reactions that enable the formation of composite products like multimetallic nanoparticles, supported nanostructures, and complex minerals. This review will examine emerging reactive laser-synthesis methods in the context of established methods like LAL. The focus will be on the chemical reactions initiated within the laser plasma, with the goal of understanding how these reactions lead to the formation of unique nanomaterials. We will provide the first systematic review of laser reaction in liquid (LRL) in the literature, and bring a focus to the chemical reaction mechanisms in LAL and reactive-LAL techniques that have not yet been emphasized in reviews. Discussion of the current challenges and future investigative opportunities into reactive laser-synthesis will impart guidance for researchers interested in designing reactive laser-synthesis approaches to novel nanomaterial production.
PubDate: 2022-04-11

• The circuit design and optimization of quantum multiplier and divider

Abstract: Abstract A fault-tolerant circuit is required for robust quantum computing in the presence of noise. Clifford + T circuits are widely used in fault-tolerant implementations. As a result, reducing T-depth, T-count, and circuit width has emerged as important optimization goals. A measure-and-fixup approach yields the best T-count for arithmetic operations, but it requires quantum measurements. This paper proposes approximate Toffoli, TR, Peres, and Fredkin gates with optimized T-depth and T-count. Following that, we implement basic arithmetic operations such as quantum modular adder and subtracter using approximate gates that do not require quantum measurements. Then, taking into account the circuit width, T-depth, and T-count, we design and optimize the circuits of two multipliers and a divider. According to the comparative analysis, the proposed multiplier and divider circuits have lower circuit width, T-depth, and T-count than the current works that do not use the measure-and-fixup approach. Significantly, the proposed second multiplier produces approximately 77% T-depth, 60% T-count, and 25% width reductions when compared to the existing multipliers without quantum measurements.
PubDate: 2022-04-08

• A unified theory of ferromagnetic quantum phase transitions in heavy
fermion metals

Abstract: Abstract Motivated by the recent discovery of a continuous ferromagnetic quantum phase transition in CeRh6Ge4 and its distinction from other U-based heavy fermion metals such as UGe2, we develop a unified explanation of their different ground state properties based on an anisotropic ferromagnetic Kondo-Heisenberg model. We employ an improved large-N Schwinger boson approach and predict a full phase diagram containing both a continuous ferromagnetic quantum phase transition for large magnetic anisotropy and first-order transitions for relatively small anisotropy. Our calculations reveal three different ferromagnetic phases including a half-metallic spin selective Kondo insulator with a constant magnetization. The Fermi surface topologies are found to change abruptly between different phases, consistent with that observed in UGe2. At finite temperatures, we predict the development of Kondo hybridization well above the ferromagnetic long-range order and its relocalization near the phase transition, in good agreement with band measurements in CeRh6Ge4. Our results highlight the importance of magnetic anisotropy and provide a unified theory for understanding the ferromagnetic quantum phase transitions in heavy fermion metals.
PubDate: 2022-04-01

• Unprotected quadratic band crossing points and quantum anomalous Hall
effect in FeB2 monolayer

Abstract: Abstract Quadratic band crossing points (QBCPs) and quantum anomalous Hall effect (QAHE) have attracted the attention of both theoretical and experimental researchers in recent years. Based on first-principle calculations, we find that the FeB2 monolayer is a nonmagnetic semimetal with QBCPs at K. Through symmetry analysis and k · p invariant theory, we find that the QBCP is not protected by rotation symmetry and consists of two Dirac points with the same chirality (Berry phase of 2π). Once introducing Coulomb interactions, we find that there is a spontaneous-time-reversal-breaking instability of the spinful QBCPs, which gives rise to a C = 2 QAH insulator with orbital moment ordering.
PubDate: 2022-04-01

JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762