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Quantum Physics Has a New, and Remarkable, Expansion
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作者 John R. Klauder 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2023年第2期467-474,共8页
Canonical quantization has taught us great things. A common example is that of the harmonic oscillator, which is like swinging a ball on a string back and forth. However, the half-harmonic oscillator blocks the ball a... Canonical quantization has taught us great things. A common example is that of the harmonic oscillator, which is like swinging a ball on a string back and forth. However, the half-harmonic oscillator blocks the ball at the bottom and then it quickly bounces backwards. This second model cannot be correctly solved using canonical quantization. Now, there is an expansion of quantization, called affine quantization, that can correctly solve the half-harmonic oscillator, and offers correct solutions to a grand collection of other problems, which even reaches to field theory and gravity. This paper has been designed to introduce affine quantization: what it is, and what it can do. 展开更多
关键词 Canonical and Affine Quantization Different Simple Examples Comments Regarding Field Theory and Gravity
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Transport in Astrophysics: V. On the Red Sun at Horizon
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作者 Lorenzo Zaninetti 《International Journal of Astronomy and Astrophysics》 2023年第4期298-310,共13页
In order to simulate the red sun at the horizon we need to evaluate the average density of matter along a line of sight characterized by a given elevation angle. The decrease in frequency or the increase in wavelength... In order to simulate the red sun at the horizon we need to evaluate the average density of matter along a line of sight characterized by a given elevation angle. The decrease in frequency or the increase in wavelength of the light is modeled by the Bouguer-Beer-Lambert law and as a consequence, all the Planck spectrum is shifted toward lower frequencies or longer wavelengths. 展开更多
关键词 Solar System General EARTH
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Transport in Astrophysics: III. Diffusion from the Galactic Plane
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作者 Lorenzo Zaninetti 《International Journal of Astronomy and Astrophysics》 2023年第1期1-24,共24页
New solutions, for the stationary and temporary states, are derived for the 1D diffusion of cosmic rays in the presence of losses. The new results are applied to the latitude profile of radiation emitted above the gal... New solutions, for the stationary and temporary states, are derived for the 1D diffusion of cosmic rays in the presence of losses. The new results are applied to the latitude profile of radiation emitted above the galactic plane. Percolation theory for a spiral galaxy coupled with the evolution of the super-bubbles allows building a model for the radiation of a spiral galaxy as seen face on. The annulus of radiation of our galaxy is also simulated and the excess of radiation observed at the centre of our galaxy is explained by the sine law which arises in the theory of the image. 展开更多
关键词 Particle Diffusion Galaxy: Centre Galaxy: Disk
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New Probability Distributions in Astrophysics: XI. Left Truncation for the Topp-Leone Distribution
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作者 Lorenzo Zaninetti 《International Journal of Astronomy and Astrophysics》 2023年第3期154-165,共12页
The Topp-Leone (T-L) distribution has aided the modeling of scientific data in many contexts. We demonstrate how it can be adapted to model astrophysical data. We analyse the left truncated version of the T-L distribu... The Topp-Leone (T-L) distribution has aided the modeling of scientific data in many contexts. We demonstrate how it can be adapted to model astrophysical data. We analyse the left truncated version of the T-L distribution, deriving its probability density function (PDF), distribution function, average value, rth moment about the origin, median, the random generation of its values, and its maximum likelihood estimator, which allows us to derive the two unknown parameters. The T-L distribution, in its regular and truncated versions, is then applied to model the initial mass function for the stars. A comparison is made with specific clusters and between proposed functions for the IMF. The Topp-Leone distribution can provide an excellent fit in some cases. 展开更多
关键词 Stars: Normal Stars: Luminosity Function Mass Function Stars: Statistics
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Transport in Astrophysics: IV. Anomalous Redshift in the Solar System
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作者 Lorenzo Zaninetti 《International Journal of Astronomy and Astrophysics》 2023年第2期61-73,共13页
The anomalous redshift on the sun’s limb and that measured by Pioneer-6 are interesting for the process of absorption of light and the spatial density of matter around the sun. Here we derive a 3D solution for the di... The anomalous redshift on the sun’s limb and that measured by Pioneer-6 are interesting for the process of absorption of light and the spatial density of matter around the sun. Here we derive a 3D solution for the diffusion equation in the case of the steady state, which is then adopted as the density of the ionized matter around the sun. In order to deal with the observed light’s intensity, two integrals along the line of sight are evaluated. Alternatives to the Doppler shift have been considered as mechanisms: a thermal model, a plasma effect, the interaction of a low density electromagnetic wave with an electron and the interaction of light with a low density Fermi gas in standard QED. These four models are compared in the case of the Pioneer-6 signal. 展开更多
关键词 Particle Diffusion Random Walks
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Global hybrid simulations of soft X-ray emissions in the Earth’s magnetosheath 被引量:1
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作者 Jin Guo TianRan Sun +6 位作者 San Lu QuanMing Lu Yu Lin XueYi Wang Chi Wang RongSheng Wang Kai Huang 《Earth and Planetary Physics》 EI CSCD 2024年第1期47-58,共12页
Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas,and it is also the boundary of the solar wind energy transport to the magnetosphere.Soft X-ray imaging ... Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas,and it is also the boundary of the solar wind energy transport to the magnetosphere.Soft X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional(2-D)global view from a satellite.By performing 3-D global hybrid-particle-in-cell(hybrid-PIC)simulations,we obtain soft X-ray images of Earth’s magnetopause under different solar wind conditions,such as different plasma densities and directions of the southward interplanetary magnetic field.In all cases,magnetic reconnection occurs at low latitude magnetopause.The soft X-ray images observed by a hypothetical satellite are shown,with all of the following identified:the boundary of the magnetopause,the cusps,and the magnetosheath.Local X-ray emissivity in the magnetosheath is characterized by large amplitude fluctuations(up to 160%);however,the maximum line-of-sight-integrated X-ray intensity matches the tangent directions of the magnetopause well,indicating that these fluctuations have limited impact on identifying the magnetopause boundary in the X-ray images.Moreover,the magnetopause boundary can be identified using multiple viewing geometries.We also find that solar wind conditions have little effect on the magnetopause identification.The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission will provide X-ray images of the magnetopause for the first time,and our global hybrid-PIC simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective,with particle kinetic effects considered. 展开更多
关键词 MAGNETOPAUSE X-ray emissivity X-ray imaging SMILE global hybrid-PIC simulation
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Finding the magnetopause location using soft X-ray observations and a statistical inverse method 被引量:1
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作者 Gonzalo Cucho-Padin Hyunju Connor +2 位作者 Jaewoong Jung Brian Walsh David G.Sibeck 《Earth and Planetary Physics》 EI CSCD 2024年第1期184-203,共20页
Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the magneto... Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the magnetosphere.The spatial and temporal properties of the magnetopause,under varying solar and magnetospheric conditions,remain largely unknown because empirical studies using in-situ observations are challenging to interpret.Global wide field-of-view(FOV)imaging is the only means to simultaneously observe the spatial distribution of the plasma properties over the vast dayside magnetospheric region and,subsequently,quantify the energy transport from the interplanetary medium into the terrestrial magnetosphere.Two upcoming missions,ESA/CAS SMILE and NASA’s LEXI will provide wide-field imagery of the dayside magnetosheath in soft X-rays,an emission generated by charge exchange interactions between high charge-state heavy ions of solar wind origin and exospheric neutral atoms.High-cadence two-dimensional observations of the magnetosheath will allow the estimation of dynamic properties of its inner boundary,the magnetopause,and enable studies of its response to changes in the solar wind dynamic pressure and interplanetary magnetic field orientation.This work introduces a statistically-based estimation approach based on inverse theory to estimate the spatial distribution of magnetosheath soft X-ray emissivities and,with this,identify the location of the magnetopause over the Sun−Earth line.To do so,we simulate the magnetosheath structure using the MHD-based OpenGGCM model and generate synthetic soft X-ray images using LEXI’s orbit and attitude information.Our results show that 3-D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray images.Also,our proposed methodology shows that the accuracy of both three-dimensional(3-D)estimation and the magnetopause standoff distance calculation highly depends on the observational point. 展开更多
关键词 MAGNETOPAUSE soft X-ray TOMOGRAPHY
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Neutral and metallic vs.charged and semiconducting surface layer in acceptor doped CeO_(2)
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作者 Ilan Riess 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第4期795-802,共8页
The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface def... The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface defects concentration in acceptor doped ceria with two different dopant types and operated under different oxygen pressures.Recently published experimental data for highly reduced Sm0.2Ce0.8O1.9-x(SDC)containing a fixed valence dopant Sm3+are very different from those published for Pr0.1Ce0.9O_(2)-x(PCO) with the variable valence dopant Pr4+/Pr3+being reduced under milder conditions.The theoretical analysis of these experimental results fits very well the experimental results of SDC and PCO.It leads to the following predictions:the highly reduced surface of SDC is metallic and neutral,the metallic surface electron density of state is gs=0.9×10^(38)J-1·m^(-2)(1.4×1015eV^(-1)·cm^(-2)),the electron effective mass is meff,s=3.3me,and the phase diagram of the reduced surface has theα(fcc)structure as in the bulk.In PCO a double layer is predicted to be formed between the surface and the bulk with the surface being negatively charged and semiconducting.The surface of PCO maintains high Pr^(3+) defect concentration as well as relative high oxygen vacancy concentration at oxygen pressures higher than in the bulk.The reasons for the difference between a metallic and semiconducting surface layer of acceptor doped CeO_(2) are reviewed,as well as the key theoretical considerations applied in coping with this problem.For that we make use of the experimental data and theoretical analysis available for acceptor doped ceria. 展开更多
关键词 CeO_(2) surface defects metallic surface oxide reduction Sm doped CeO_(2) Pr doped CeO_(2)
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Nuclear charge radius predictions by kernel ridge regression with odd-even effects
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作者 Lu Tang Zhen-Hua Zhang 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第2期94-102,共9页
The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models.These are:(i)the isospin-dependent A^(... The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models.These are:(i)the isospin-dependent A^(1∕3) formula,(ii)relativistic continuum Hartree-Bogoliubov(RCHB)theory,(iii)Hartree-Fock-Bogoliubov(HFB)model HFB25,(iv)the Weizsacker-Skyrme(WS)model WS*,and(v)HFB25*model.In the last two models,the charge radii were calculated using a five-parameter formula with the nuclear shell corrections and deformations obtained from the WS and HFB25 models,respectively.For each model,the resultant root-mean-square deviation for the 1014 nuclei with proton number Z≥8 can be significantly reduced to 0.009-0.013 fm after considering the modification with the EKRR method.The best among them was the RCHB model,with a root-mean-square deviation of 0.0092 fm.The extrapolation abilities of the KRR and EKRR methods for the neutron-rich region were examined,and it was found that after considering the odd-even effects,the extrapolation power was improved compared with that of the original KRR method.The strong odd-even staggering of nuclear charge radii of Ca and Cu isotopes and the abrupt kinks across the neutron N=126 and 82 shell closures were also calculated and could be reproduced quite well by calculations using the EKRR method. 展开更多
关键词 Nuclear charge radius Machine learning Kernel ridge regression method
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RPL-Based IoT Networks under Decreased Rank Attack:Performance Analysis in Static and Mobile Environments
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作者 Amal Hkiri Mouna Karmani +3 位作者 Omar Ben Bahri Ahmed Mohammed Murayr Fawaz Hassan Alasmari Mohsen Machhout 《Computers, Materials & Continua》 SCIE EI 2024年第1期227-247,共21页
The RPL(IPv6 Routing Protocol for Low-Power and Lossy Networks)protocol is essential for efficient communi-cation within the Internet of Things(IoT)ecosystem.Despite its significance,RPL’s susceptibility to attacks r... The RPL(IPv6 Routing Protocol for Low-Power and Lossy Networks)protocol is essential for efficient communi-cation within the Internet of Things(IoT)ecosystem.Despite its significance,RPL’s susceptibility to attacks remains a concern.This paper presents a comprehensive simulation-based analysis of the RPL protocol’s vulnerability to the decreased rank attack in both static andmobilenetwork environments.We employ the Random Direction Mobility Model(RDM)for mobile scenarios within the Cooja simulator.Our systematic evaluation focuses on critical performance metrics,including Packet Delivery Ratio(PDR),Average End to End Delay(AE2ED),throughput,Expected Transmission Count(ETX),and Average Power Consumption(APC).Our findings illuminate the disruptive impact of this attack on the routing hierarchy,resulting in decreased PDR and throughput,increased AE2ED,ETX,and APC.These results underscore the urgent need for robust security measures to protect RPL-based IoT networks.Furthermore,our study emphasizes the exacerbated impact of the attack in mobile scenarios,highlighting the evolving security requirements of IoT networks. 展开更多
关键词 RPL decreased rank attacks MOBILITY random direction model
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Three-Wave Mixing of Dipole Solitons in One-Dimensional Quasi-Phase-Matched Nonlinear Crystals
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作者 郭宇欣 徐晓喜 +5 位作者 陈招拼 周延桂 刘彬 和河向 黎永耀 谢嘉宁 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第1期25-33,共9页
A quasi-phase-matched technique is introduced for soliton transmission in a quadratic[χ^((2))]nonlinear crystal to realize the stable transmission of dipole solitons in a one-dimensional space under three-wave mixing... A quasi-phase-matched technique is introduced for soliton transmission in a quadratic[χ^((2))]nonlinear crystal to realize the stable transmission of dipole solitons in a one-dimensional space under three-wave mixing.We report four types of solitons as dipole solitons with distances between their bimodal peaks that can be laid out in different stripes.We study three cases of these solitons:spaced three stripes apart,one stripe apart,and confined to the same stripe.For the case of three stripes apart,all four types have stable results,but for the case of one stripe apart,stable solutions can only be found atω_(1)=ω_(2),and for the condition of dipole solitons confined to one stripe,stable solutions exist only for Type1 and Type3 atω_(1)=ω_(2).The stability of the soliton solution is solved and verified using the imaginary time propagation method and real-time transfer propagation,and soliton solutions are shown to exist in the multistability case.In addition,the relations of the transportation characteristics of the dipole soliton and the modulation parameters are numerically investigated.Finally,possible approaches for the experimental realization of the solitons are outlined. 展开更多
关键词 SOLITON SOLITONS DIPOLE
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Dynamical t/U Expansion of the Doped Hubbard Model
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作者 丁文新 俞榕 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第3期73-82,共10页
We construct a new U(1)slave-spin representation for the single-band Hubbard model in the large-U limit.The mean-field theory in this representation is more amenable to describe both the spin-charge-separation physics... We construct a new U(1)slave-spin representation for the single-band Hubbard model in the large-U limit.The mean-field theory in this representation is more amenable to describe both the spin-charge-separation physics of the Mott insulator at half-filling and the strange metal behavior at finite doping. 展开更多
关键词 HUBBARD REPRESENTATION SEPARATION
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Electromagnetic fields in ultra-peripheral relativistic heavy-ion collisions
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作者 Jie Zhao Jin-Hui Chen +1 位作者 Xu-Guang Huang Yu-Gang Ma 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第2期103-109,共7页
Ultra-peripheral heavy-ion collisions(UPCs)offer unique opportunities to study processes under strong electromagnetic fields.In these collisions,highly charged fast-moving ions carry strong electromagnetic fields that... Ultra-peripheral heavy-ion collisions(UPCs)offer unique opportunities to study processes under strong electromagnetic fields.In these collisions,highly charged fast-moving ions carry strong electromagnetic fields that can be effectively treated as photon fluxes.The exchange of photons can induce photonuclear and two-photon interactions and excite ions.This excitation of the ions results in Coulomb dissociation with the emission of photons,neutrons,and other particles.Additionally,the electromagnetic fields generated by the ions can be sufficiently strong to enforce mutual interactions between the two colliding ions.Consequently,the two colliding ions experience an electromagnetic force that pushes them in opposite directions,causing a back-to-back correlation in the emitted neutrons.Using a Monte Carlo simulation,we qualitatively demonstrate that the above electromagnetic effect is large enough to be observed in UPCs,which would provide a clear means to study strong electromagnetic fields and their effects. 展开更多
关键词 Electromagnetic fields Neutrons Ultra-peripheral relativistic heavy-ion collisions(UPC)
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Final results of the first phase of the PROTO-SPHERA experiment: obtainment of the full current stable screw pinch and first evidences of the jet + torus combined plasma configuration
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作者 Paolo MICOZZI Franco ALLADIO +21 位作者 Alessandro MANCUSO Vincenzo ZANZA Gerarda APRUZZESE Francesca BOMBARDA Luca BONCAGNI Paolo BURATTI Francesco FILIPPI Giuseppe GALATOLA TEKA Francesco GIAMMANCO Edmondo GIOVANNOZZI Andrea GROSSO Matteo IAFRATI Alessandro LAMPASI Violeta LAZIC Simone MAGAGNINO Simone MANNORI Paolo MARSILI Valerio PIERGOTTI Giuliano ROCCHI Alessandro SIBIO Benedetto TILIA Onofrio TUDISCO 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第2期31-43,共13页
In astrophysics, the boundary conditions for plasma phenomena are provided by nature and the astronomer faces the problem of understanding them from a variety of observations [Hester J J et al 1996 Astrophys. J. 456 2... In astrophysics, the boundary conditions for plasma phenomena are provided by nature and the astronomer faces the problem of understanding them from a variety of observations [Hester J J et al 1996 Astrophys. J. 456 225], on the other hand, in laboratory plasma experiments the electromagnetic boundary conditions become a major problem in the set-up of the machine that produces the plasma, an issue that has to be investigated step by step and to be modified and adapted with great patience, in particular in the case of an innovative plasma confinement experiment. The PROTO-SPHERA machine [Alladio F et al 2006 Nucl. Fusion 46 S613] is a magnetic confinement experiment, that emulates in the laboratory the jet + torus plasma configurations often observed in astrophysics: an inner magnetized jet of plasma centered on the(approximate) axis of symmetry and surrounded by a magnetized plasma torus orthogonal to this jet. The PROTO-SPHERA plasma is simply connected, i.e., no metal current conducting rod is linked to the plasma torus, while instead it is the inner magnetized plasma jet(in the following always called the plasma centerpost) that is linked to the torus. It is mandatory that no spurious plasma current path modifies the optimal shape of the plasma centerpost. Moreover, as the plasma torus is produced and sustained, in absence of any applied inductive electric field, by the inner plasma centerpost through magnetic reconnections [Taylor J B and Turner M F 1989 Nucl.Fusion 29 219], it is required as well that spurious current paths do not surround the torus on its outboard, in order not to lower the efficiency of the magnetic reconnections that maintain the plasma torus at the expense of the plasma centerpost. Boundary conditions have been corrected,up to the point that the first sustainment in steady state has been achieved for the combined plasma. 展开更多
关键词 laboratory plasmas magnetic confinement astrophysical plasmas
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Cholesterol-induced deformation of the gramicidin A channel inhibiting potassium ion binding and transport
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作者 肖盼 曹宇 +1 位作者 朱瑾 梁清 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期696-702,共7页
Gramicidin A(gA)is a kind of antibiotic peptide produced by bacillus brevis and it can dimerize across lipid bilayers to form a monovalent cation channel.In this work,we investigate the impact of cholesterol in the li... Gramicidin A(gA)is a kind of antibiotic peptide produced by bacillus brevis and it can dimerize across lipid bilayers to form a monovalent cation channel.In this work,we investigate the impact of cholesterol in the lipid bilayer on the binding of potassium ions with the gA channel and the transport of the ions across the channel.The results indicate that cholesterol can significantly influence the conformational stability of the gA channel and cause the channel deformation which inhibits the potassium ion binding with the channel and transport across the channel.The work provides some molecular insights into understanding of influence of lipids on the activity of gA channel in both model membranes and plasma membranes of intact cells. 展开更多
关键词 gramicidin A lipid bilayer molecular dynamics interaction
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Spatial search weighting information contained in cell velocity distribution
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作者 马一凯 李娜 陈唯 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期522-528,共7页
Cell migration plays a significant role in physiological and pathological processes.Understanding the characteristics of cell movement is crucial for comprehending biological processes such as cell functionality,cell ... Cell migration plays a significant role in physiological and pathological processes.Understanding the characteristics of cell movement is crucial for comprehending biological processes such as cell functionality,cell migration,and cell–cell interactions.One of the fundamental characteristics of cell movement is the specific distribution of cell speed,containing valuable information that still requires comprehensive understanding.This article investigates the distribution of mean velocities along cell trajectories,with a focus on optimizing the efficiency of cell food search in the context of the entire colony.We confirm that the specific velocity distribution in the experiments corresponds to an optimal search efficiency when spatial weighting is considered.The simulation results indicate that the distribution of average velocity does not align with the optimal search efficiency when employing average spatial weighting.However,when considering the distribution of central spatial weighting,the specific velocity distribution in the experiment is shown to correspond to the optimal search efficiency.Our simulations reveal that for any given distribution of average velocity,a specific central spatial weighting can be identified among the possible central spatial weighting that aligns with the optimal search strategy.Additionally,our work presents a method for determining the spatial weights embedded in the velocity distribution of cell movement.Our results have provided new avenues for further investigation of significant topics,such as relationship between cell behavior and environmental conditions throughout their evolutionary history,and how cells achieve collective cooperation through cell-cell communication. 展开更多
关键词 cell migration foraging efficiency random walk spatial search weight
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Detection of Gravitational Waves with Semi Classical Features and Resulting Cosmological Implications
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作者 Andrew Walcott Beckwith 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期454-467,共14页
The author argues in this document that initial vacuum state values possibly responsible for GW generation in relic conditions in the initial onset of inflation may have a temporary unsqueezed, possibly even coherent ... The author argues in this document that initial vacuum state values possibly responsible for GW generation in relic conditions in the initial onset of inflation may have a temporary unsqueezed, possibly even coherent initial value, which would permit in certain models classical coherent initial gravitational wave states. Furthermore, several arguments pro and con as to if or not initial relic GW should be high frequency will be presented, with the reason given why earlier string models did NOT favor low frequency relic GW from the big bang. What is observed is that large higher dimensions above our 4 Dimensional space time, if recipients of matter-energy from collapse and re birth of the universe are enough to insure low relic GW. The existence of higher dimensions, in itself if the additional dimensions are small and compact will have no capacity to lower the frequency limit values of relic GW, as predicted by Giovannini, et al. in 1995. 展开更多
关键词 Graviton DM Squeezed States Coherent States High Frequency Gravity Waves
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Classical Cosmology II. The Einstein Ring
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作者 Lorenzo Zaninetti 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第2期574-598,共25页
The Einstein ring is usually explained in the framework of the gravitational lens. Conversely here we apply the framework of the expansion of a superbubble (SB) in order to explain the spherical appearance of the ring... The Einstein ring is usually explained in the framework of the gravitational lens. Conversely here we apply the framework of the expansion of a superbubble (SB) in order to explain the spherical appearance of the ring. Two classical equations of motion for SBs are derived in the presence of a linear and a trigonometric decrease for density. A relativistic equation of motion with an inverse square dependence for the density is derived. The angular distance, adopting the minimax approximation, is derived for three relativistic cosmologies: the standard, the flat and the wCDM. We derive the relation between redshift and Euclidean distance, which allows fixing the radius of the Einstein ring. The details of the ring are explained by a simple version of the theory of images. 展开更多
关键词 COSMOLOGY Observational Cosmology Gravitational Lenses Luminous Arcs
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Enhanced measurement precision with continuous interrogation during dynamical decoupling
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作者 张军 杜鹏 +3 位作者 敬雷 徐鹏 尤力 张文献 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期88-94,共7页
Dynamical decoupling(DD)is normally ineffective when applied to DC measurement.In its straightforward implementation,DD nulls out DC signal as well while suppressing noise.This work proposes a phase relay method that ... Dynamical decoupling(DD)is normally ineffective when applied to DC measurement.In its straightforward implementation,DD nulls out DC signal as well while suppressing noise.This work proposes a phase relay method that is capable of continuously interrogating the DC signal over many DD cycles.We illustrate its efficacy when applied to the measurement of a weak DC magnetic field with an atomic spinor Bose-Einstein condensate.Sensitivities approaching standard quantum limit or Heisenberg limit are potentially realizable for a coherent spin state or a squeezed spin state of 10000 atoms,respectively,while ambient laboratory level noise is suppressed by DD.Our work offers a practical approach to mitigate the limitations of DD to DC measurement and would find other applications for resorting coherence in quantum sensing and quantum information processing research. 展开更多
关键词 quantum sensing continuous interrogation quantum magnetometer dynamical decoupling Heisenberg limit
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Low-energy spin dynamics in a Kitaev material Na_(3)Ni_(2)BiO_(6) investigated by nuclear magnetic resonance
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作者 史昕雨 崔祎 +11 位作者 上官艳艳 徐霄宇 吴占龙 胡泽 李硕 杜柯帆 陈颖 马龙 刘正鑫 温锦生 张金珊 于伟强 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第6期518-524,共7页
We perform ^(23)Na nuclear magnetic resonance(NMR) and magnetization measurements on an S=1,quasi-2D honeycomb lattice antiferromagnet Na_(3)Ni_(2)BiO_(6).A large positive Curie-Weiss constant of 22.9 K is observed.Th... We perform ^(23)Na nuclear magnetic resonance(NMR) and magnetization measurements on an S=1,quasi-2D honeycomb lattice antiferromagnet Na_(3)Ni_(2)BiO_(6).A large positive Curie-Weiss constant of 22.9 K is observed.The NMR spectra at low fields are consistent with a zigzag magnetic order,indicating a large easy-axis anisotropy.With the field applied along the c*axis,the NMR spectra confirm the existence of a 1/3-magnetization plateau phase between 5.1 T and 7.1 T.The transition from the zigzag order to the 1/3-magnetization plateau phase is also found to be a first-order type.A monotonic decrease of the spin gap is revealed in the 1/3-magnetization plateau phase,which reaches zero at a quantum critical field H_(C)≈8.35 T before entering the fully polarized phase.These data suggest the existence of exchange frustration in the system along with strong ferromagnetic interactions,hosting the possibility for Kitaev physics.Besides,well below the ordered phase,the 1/T_(1) at high fields shows either a level off or an enhancement upon cooling below 3 K,which suggests the existence of low-energy fluctuations. 展开更多
关键词 one–third magnetization plateau phase nuclear magnetic resonance honeycomb-lattice antiferromagnet Kitaev interaction
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