Are avalanches in sandpiles a chaotic phenomenon?

We show that deterministic systems with strong nonlinearities seem to be more appropriate to model sandpiles than stochastic systems or deterministic systems in which discontinuities are the only nonlinearity. In particular, we are able to reproduce the breakdown of self-organized criticality found in two well known experiments, that is, a centrally fueled pile [Phys. Rev. Lett. 65 (1990) 1120] and sand in a rotating tray [Phys. Rev. Lett. 69 (1992) 2431]. By varying the parameters of the model we recover self-organized criticality, in agreement with other experiments and other models. We show that chaos plays a fundamental role in the dynamics of the system.     

Observation of Periodic Multiplication and Chaotic Phenomena in Atmospheric Cold Plasma Jets

We investigate the temporal evolution of the current pulses from an ac Fie cold plasma jet at atmospheric pressure and with driving frequency in the range 14.76-15.30 kHz. The driving frequency is used as the plasma system＇s bifurcation parameter in analogy with the evolution in which the current pulses undergoes multiplication and chaos. Such time-domain nonlineaxity is important for controlling instabilities in atmospheric glow discharges. In addition, the observation can provide some data to support the simulation results reported previously [Appl. Phys. Lett. 90 （2007） 071501].     

Analysis of volume dependence of Grüneisen ratio

Various models on volume dependence of the Grüneisen ratio have been analyzed in the present study. The Sharma model [Mod. Phys. Lett. B 22/31 (2008) 3113] is found to be similar to that used by Nie [Phys. Stat. Sol. (b) 219 (2004) 241] on the basis of approximation made by Jeanloz [J. Geophys. Res. 94 (1989) 5929]. The Nie expression is amended in a manner so that the resulted expression follows the constraint of high pressure thermodynamics in the limit of infinite pressure. The newly developed relationship is applied successfully on materials for which experimental data are accessible such as epsilon-iron, NaCl, Li, Na, and K.     

A Model Study of Equation of State of QCD at Finite Chemical Potential and Zero Temperature

In this paper, we give a direct method for calculating the partition function, and hence the equation of state （EOS） of QCD at finite chemical potential and zero temperature. In the EOS derived in this paper the pressure density is the sum of two terms： the first term P（μ）｜μ=0 （the pressure density at μ = 0） is a μ-independent constant; the second term, which is totally determined by G[μ] （p） （the dressed quark propagator at finite μ）, contains all the nontrivial μ-dependence. By applying a general result in the rainbow-ladder approximation of the Dyson-Schwinger approach obtained in our previous study [Phys. Rev. C 71 （2005） 015205], G[μ]（p） is calculated from the meromorphic quark propagator proposed in [Phys. Rev. D 67 （2003） 054019]. From this the full analytic expression of the EOS of QCD at finite μ and zero T is obtained （apart from the constant term P（μ）｜μ=0, which can in principle be caJculated from the CJT effective action）. A comparison between our EOS and the cold, perturbative EOS of QCD of Fraga, Pisarski and Schaffner-Bielich is made. It is expected that our EOS can provide a possible new approach for the study of neutron stars.     

Evidence for nanoparticles in microwave-generated fireballs observed by synchrotron x-ray scattering

The small-angle x-ray scattering method has been applied to study fireballs ejected into the air from molten hot spots in borosilicate glass by localized microwaves [V. Dikhtyar and E. Jerby, Phys. Rev. Lett. 96 045002 (2006)10.1103/PhysRevLett.96.045002]. The fireball's particle size distribution, density, and decay rate in atmospheric pressure were measured. The results show that the fireballs contain particles with a mean size of approximately 50 nm with average number densities on the order of approximately 10(9). Hence, fireballs can be considered as a dusty plasma which consists of an ensemble of charged nanoparticles in the plasma volume. This finding is likened to the ball-lightning phenomenon explained by the formation of an oxidizing particle network liberated by lightning striking the ground [J. Abrahamson and J. Dinniss, Nature (London) 403, 519 (2000)10.1038/35000525].     

Projectile interactions in granular impact cratering

We present evidence for the interactions between a ball and the container boundaries, as well as between two balls, that are mediated by the granular medium during impact cratering. The presence of the bottom boundary affects the final penetration depth only for low drop heights with shallow filling, in which case, surprisingly, the penetration becomes deeper. By contrast the presence of the sidewall causes less penetration and also an effective repulsion. Repulsion is also found for two balls dropped side by side.     

Hosing instability in the blow-out regime for plasma-wakefield acceleration

The electron hosing instability in the blow-out regime of plasma-wakefield acceleration is investigated using a linear perturbation theory about the electron blow-out trajectory in Lu et al. [in Phys. Rev. Lett. 96, 165002 (2006)10.1103/PhysRevLett.96.165002]. The growth of the instability is found to be affected by the beam parameters unlike in the standard theory Whittum et al. [Phys. Rev. Lett. 67, 991 (1991)10.1103/PhysRevLett.67.991] which is strictly valid for preformed channels. Particle-in-cell simulations agree with this new theory, which predicts less hosing growth than found by the hosing theory of Whittum et al.     

基于六粒子纠缠态和Bell态测量的量子信息分离

通过介绍六粒子纠缠态的新应用研究,提出了一个二粒子任意态的信息分离方案.在这个方案中,发送者Alice、控制者Charlie和接受者Bob共享一个六粒子纠缠态,发送者先执行两次Bell基测量|然后控制者执行一次Bell基测量|最后接受者根据发送者和控制者的测量结果,对自己拥有的粒子做适当的幺正变换,从而能够重建要发送的二粒子任意态.这个信息分离方案是决定性的,即成功概率为100%.与使用相同的量子信道进行二粒子任意态的信息分离方案相比,本文提出的方案只需要进行Bell基测量而不需要执行多粒子的联合测量,从而使得这个方案更简单、更容易,并且在目前的实验室技术条件下是能够实现的.     

Electron impinging on metallic thin film targets

Based on the Vicanek and Urbassek theory [M. Vicanek, H.M. Urbassek, Phys. Rev. B 44 (1991) 7234] combined to a home-made Monte Carlo simulation, the present work deals with backscattering coefficients, mean penetration depths and stopping profiles for 1-4 keV electrons normally incident impinging on Al and Cu thin film targets. The cross-sections used to describe the electron transport are calculated via the appropriate analytical expression given by Jablonski [A. Jablonski, Phys. Rev. B 58 (1998) 16470] whose new improved version has been recently given [Z. Rouabah, N. Bouarissa, C. Champion, N. Bouaouadja, Appl. Surf. Sci. 255 (2009) 6217]. The behavior of the backscattering coefficient, mean penetration depth and stopping profiles versus the metallic film thickness at the nanometric scale and beyond is here analyzed and discussed.     

Observation of fractional Stokes-Einstein behavior in the simplest hydrogen-bonded liquid

Quasielastic neutron scattering has been used to investigate the single-particle dynamics of hydrogen fluoride across its entire liquid range at ambient pressure. For T>230 K, translational diffusion obeys the celebrated Stokes-Einstein relation, in agreement with nuclear magnetic resonance studies. At lower temperatures, we find significant deviations from the above behavior in the form of a power law with exponent xi=-0.71+/-0.05. More striking than the above is a complete breakdown of the Debye-Stokes-Einstein relation for rotational diffusion. Our findings provide the first experimental verification of fractional Stokes-Einstein behavior in a hydrogen-bonded liquid, in agreement with recent computer simulations [S. R. Becker, Phys. Rev. Lett. 97, 055901 (2006)10.1103/PhysRevLett.97.055901].     

Spectra of sonoluminescent rare-Gas bubbles

Sonoluminescence spectra of the heavy rare gases are calculated by combining the Hilgenfeldt et al. model of sonoluminescence [Phys. Fluids 11, 1318 (1999)] with quantum line-shape calculations of electron-neutral-atom bremsstrahlung spectra [L. Frommhold, Phys. Rev. E 58, 1899 (1998)]. Good agreement between theoretical and experimental spectra is obtained by choosing values of the ambient radius R0 and acoustic pressure amplitude P(a) that are compatible with diffusive equilibrium calculations.     

Phase diagram of planar U(1)×U(1) superconductor: Condensation of vortices with fractional flux and a superfluid state

We discuss a phase diagram of two-dimensional U(1)×U(1) superconductor in the field theoretic formalizm of [Phys. Rev. Lett. 89 (2002) 067001]. In particular we discuss that when penetration length is short the system exhibit a quasi-neutral quasi-superfluid state which is a state when quasi-long range order sets in only in phase difference while individually the phases are disordered.     

Semiclassical investigation of Coulomb focusing effects in atomic above-threshold ionization with elliptically polarized laser fields

We investigate atomic above-threshold ionization in elliptically polarized strong laser fields with a semiclassical approach.With increasing laser intensity,the Coulomb focusing(CF) effects are found to become stronger in both parallel and perpendicular directions with respect to the polarization plane.The dependence of CF effects on tunnel exit,initial transverse momentum distribution and laser electric field is analyzed.It was revealed that the effects of tunnel exit are most prominent with variation of the laser intensity,and the other two factors both play non-negligible roles.Our results provide a deeper insight to the recent experiments of Coulomb asymmetry[Shafir D,et al.,2013 Phys.Rev.Lett.111 023005 and Li M,et al,2013 Phys.Rev.Lett.111 023006].     

Sigma Terms and Strangeness Contents of Baryon Octet in Modified Chiral Perturbation Theory

[1]J.Gasser,H.Leutwyler,and M.E.Sainio,Phys.Lett.B 253 (1991) 252. [2]John Ellis,Eur.Phys.J.A 24S2 (2005) 3,[arXive:hepph/0411369]. [3]T.Inoue,V.E.Lyubovitskij,Th.Gutsche,and Amand Faessler,Phys.Rev.C 69 (2004) 035207,[arXive:hepph/0311275]. [4]M.M.Pavan,I.I.Strakovsky,R.L.Workman,and R.A.Arndt,PiN Newslett.16 (2002) 110,[arXive:hepph/0111066]. [5]V.E.Lyubovitskij,Th.Gutsche,Amand Faessler,and E.G.Drukarev,Phys.Rev.D 63 (2001) 054026,[arXive:hep-ph/0009341]. [6]S.D.Bass,Phys.Lett.B 329 (1994) 358,[arXive:hepph/9404294]. [7]Marc Knecht,PiN Newslett.15 (1999) 108,[arXive:hepph/9912443]. [8]P.Schweitzer,Phys.Rev.D 69 (2004) 034003. [9]B.C.Lehnhart,J.Gegelia,and S.Scherer,J.Phys.G 31(2005) 89,[arXive:hep-ph/0412092]. [10]P.J.Ellis and K.Torikoshi,Phys.Rev.C 61 (1999)015205. [11]Gerald E.Hite,William B.Kaufmann,and Richard J.Jacob,Phys.Rev.C 71 (2005) 065201. [12]S.Weinberg,Physica A 96 (1979) 327. [13]J.Gasser and H.Leutwyler,Nucl.Phys.B 250 (1985)465. [14]J.Gasser,M.E.Sainio,and A.Svarc,Nucl.Phys.B 307(1988) 779. [15]P.Papazoglou,D.Zschiesche,S.Schramm,J.SchaffnerBielich,H.St(o)cker,and W.Greiner,Phys.Rev.C 59(1999) 411. [16]T.Fuchs and J.Gegelia,Phys.Rev.D 68 (2003) 056005.     

Electronic reconstruction at SrMnO3-LaMnO3 superlattice interfaces

We use resonant soft-x-ray scattering (RSXS) to study the electronic reconstruction at the interface between the Mott insulator LaMnO3 and the band insulator SrMnO3. Superlattices of these two insulators were shown previously to have both ferromagnetism and metallic tendencies [Koida, Phys. Rev. B 66, 144418 (2002)10.1103/PhysRevB.66.144418]. By studying a judiciously chosen superlattice reflection, we show that the interface density of states exhibits a pronounced peak at the Fermi level, similar to that predicted in related titanate superlattices by Okamoto et al. [Phys. Rev. B 70, 241104(R) (2004)10.1103/PhysRevB.70.241104]. The intensity of this peak correlates with the conductivity and magnetization, suggesting it is the driver of metallic behavior. Our study demonstrates a general strategy for using RSXS to probe the electronic properties of heterostructure interfaces.     

Heat Capacity Under Pressure of CeCoIn 5

Among heavy-fermion (HF) superconductors, CeCoIn 5 exhibits a record high value of T c =2.3 K at ambient pressure [1]. CeCoIn 5 belongs to a new class of HF-superconductors that crystallize in the tetragonal HoCoGa 5 -structure. This structure can be regarded as alternating layers of CeIn 3 and CoIn 2 . Bulk CeIn 3 undergoes a transition from an antiferromagnetic (AFM) state at ambient pressure ( T N =10.2 K) to a superconducting state with very low T C =0.15 K at a critical pressure p c =2.8 GPa [2] at which long range magnetic order vanishes. It is, therefore, regarded as a possible candidate for magnetically mediated superconductivity (SC). We report on measurements of the heat capacity of CeCoIn 5 at hydrostatic pressures p h 1.5 GPa. While T c increases with increasing pressure, the effective mass of the quasi-particles m eff decreases, as indicated by the ratio C / T | T c . As a working hypothesis based on theories of a nearly antiferromagnetic Fermi-liquid (NAFFL), this may be interpreted as the stabilization of the superconducting state by an increase of the characteristic spin fluctuation temperature T_{SF} (T_{SF}\propto k_F^2/m_{\rm eff}).     

Impact on soft sand: void collapse and jet formation

Very fine sand is prepared in a well-defined and fully decompactified state by letting gas bubble through it. After turning off the gas stream, a steel ball is dropped on the sand. On impact of the ball, sand is blown away in all directions ("splash") and an impact crater forms. When this cavity collapses, a granular jet emerges and is driven straight into the air. A second jet goes downwards into the air bubble entrained during the process, thus pushing surface material deep into the ground. The air bubble rises slowly towards the surface, causing a granular eruption. In addition to the experiments and the discrete particle simulations we present a simple continuum theory to account for the void collapse leading to the formation of the upward and downward jets.     

Third-order elastic constants of diamond determined from experimental data

The pressure derivatives of the second-order elastic constants (SOECs) of diamond were determined by analyzing previous sound velocity measurements under hydrostatic stress [McSkimin and Andreatch, J. Appl. Phys., vol. 43, 1972, pp. 2944] [4]. Our analysis corrects an error in the previously reported results. Using the corrected pressure derivatives, together with published data for the nonlinear elastic response of shock-compressed diamond [Lang and Gupta, Phys. Rev. Lett., vol. 106, 2011, pp. 125502] [3], a complete and corrected set of third-order elastic constants (TOECs) is presented that differs significantly from TOECs published previously.     

Ignition of hexane-air mixtures by highly under-expanded hot jets

We report an experimental study of ignition of flammable mixtures by highly unexpanded, supersonic hot jets. The high-pressure, hot-gas reservoir supplying the jet is created by impacting a projectile on a plunger to rapidly compress and ignite a rich n-hexane/air mixture, resulting in a peak reservoir pressure of more than 20 MPa. A locking mechanism was used to prevent the plunger from rebounding and the jet was created by rupturing a diaphragm covering a nozzle with an exit diameter between 0.25 and 1 mm. The jet development and ignition processes in the main chamber filled with hexane-air mixture were visualized using high-speed schlieren and OH* chemiluminescence imaging. The ignition threshold was determined as a function of composition in the jet and main chamber, the nozzle diameter, and the initial pressure in the main chamber. Unlike the case of subsonic jets in which ignition occurs at the shear layer near the nozzle exit, ignition of combustion in the main chamber was found to take place downstream of the Mach disk terminating the supersonic expansion and within the turbulent mixing region created by the startup of the supersonic jet. The results are interpreted using a constant-pressure, well-stirred reactor model simulating the mixing between the hot jet and cold ambient gas. The critical conditions for ignition are determined by the competition between energy release due to chemical reactions initiated by the hot jet gas and cooling due to mixing with the cold chamber atmosphere. The critical value (maximum for which ignition occurs) of the mixing rate was computed using a detailed chemical reaction model and found to be a useful qualitative guide to our observations.