Search

We present a measurement of the W boson mass using data corresponding to 4.3 fb-1 of integrated luminosity collected with the DO detector during Run II at the Fermilab Tevatron pp― collider. With a sample of 1 677 394 W → ev candidate events, we measure Mw = 80.367 ± 0.026 GeV. This result is combined with an earlier D0 result determined using an independent Run II data sample, corresponding to 1 fb-1 of integrated luminosity, to yield Mw = 80.375 ± 0.023 GeV. [ABSTRACT FROM AUTHOR]

We have measured the W-boson mass Mw using data corresponding to 2.2 fb-1 of integrated luminosity collected in pp― collisions at √s = 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470 126 W → ev candidates and 624708 W → μν candidates yield the measurement Mw = 80387 ± 12staL ± 15sysL = 80387 ± 19 MeV/c2. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined. [ABSTRACT FROM AUTHOR]

In this Letter, we compute the three-loop corrections to the beta functions of the three gauge couplings in the standard model of particle physics using the minimal subtraction scheme and taking into account Yukawa and Higgs self-couplings. [ABSTRACT FROM AUTHOR]

In this study we discuss the performance of the special quasirandom structure (SQS) method in predicting the elastic properties of Bl (rocksalt) Tio.5Alo.5N alloy. We use a symmetry-based projection technique, which gives the closest cubic approximate of the elastic tensor and allows us to align the SQSs of different shapes and sizes for a comparison in modeling elastic tensors. We show that the derived closest cubic approximate of the elastic tensor converges faster with respect to SQS size than the elastic tensor itself. That establishes a less demanding computational strategy to achieve convergence for the elastic constants. We determine the cubic elastic constants (Cij) and Zener's type elastic anisotropy (A) of Ti0.5Al0.5N. Optimal supercells, which capture accurately both the configurational disorder and cubic symmetry of elastic tensor, result in C11 = 447 GPa, C12 = 158 GPa, and C44 = 203 GPa with 3% of error and A = 1.40 with 6% of error. In addition, we establish the general importance of selecting proper SQS with symmetry arguments to reliably model elasticity of alloys. We suggest the calculation of nine elastic tensor elements: C11, C22, C33, C12, C13, C23, C44, C55, and C66, to analyze the performance of SQSs and predict elastic constants of cubic alloys. The described methodology is general enough to be extended for alloys with other symmetry at arbitrary composition. [ABSTRACT FROM AUTHOR]

We report on the first realistic ab initio calculation of a hadronic weak decay, that of the amplitude A2 for a kaon to decay into two IT mesons with isospin 2. We find ReA2 = (1.436 ± 0.063stat ± 0.258syst)10-8 GeV in good agreement with the experimental result and for the hitherto unknown imaginary part we find ImA2 = --(6.83 ± 0.51stat ± 1.30syst)10-13 GeV. Moreover combining our result for ImA2 with experimental values of ReA2, ReA0, and E1/E, we obtain the following value for the unknown ratio ImA0/ReA0 within the standard model: ImA0/ReA0 = --1.63(19)stat(20)syst × 10-4. One consequence of these results is that the contribution from ImA2 to the direct CP violation parameter E1 (the so-called Electroweak Penguin contribution) is Re(E1/E)EWP = -(6.52 ± 0.49stat ± 1.24syst) × 10-4. We explain why this calculation of A2 represents a major milestone for lattice QCD and discuss the exciting prospects for a full quantitative understanding of CP violation in kaon decays. [ABSTRACT FROM AUTHOR]

We present a general strategy to simulate a D + 1-dimensional quantum system using a D-dimensional one. We analyze in detail a feasible implementation of our scheme using optical lattice technology. The simplest nontrivial realization of a fourth dimension corresponds to the creation of a bi-volume geometry. We also propose single- and many-particle experimental signatures to detect the effects of the extra dimension. [ABSTRACT FROM AUTHOR]

The Fermi surface of graphite has been mapped out using de Haas-van Alphen (dHvA) measurements at low temperature with in-situ rotation. For tilt angles θ > 60° between the magnetic field and the c axis, the majority electron and hole dHvA periods no longer follow a cos(θ) behavior demonstrating that graphite has a three-dimensional closed Fermi surface. The Fermi surface of graphite is accurately described by highly elongated ellipsoids. A comparison with the calculated Fermi surface suggests that the Slonczewski-Weiss-McClure trigonal warping parameter γ3 is significantly larger than previously thought. [ABSTRACT FROM AUTHOR]

We report a new mechanism that does not require the formation of interfacial dislocations to mediate spiral growth during molecular beam epitaxy of Bi2Se3. Based on in situ scanning tunneling microscopy observations, we find that Bi2Se3 growth on epitaxial graphene/SiC(0001) initiates with two-dimensional (2D) nucleation, and that the spiral growth ensues with the pinning of the 2D growth fronts at jagged steps of the substrate or at domain boundaries created during the coalescence of the 2D islands. Winding of the as-created growth fronts around these pinning centers leads to spirals. The mechanism can be broadly applied to the growth of other van der Waals materials on weakly interacting substrates. We further confirm, using scanning tunneling spectroscopy, that the one-dimensional helical mode of a line defect is not supported in strong topological insulators such as Bi2Se3. [ABSTRACT FROM AUTHOR]

A novel regime is proposed where, by employing linearly polarized laser pulses at intensities 1021 W cm-2 (2 orders of magnitude lower than discussed in previous work [T. Esirkepov et al, Phys. Rev. Lett. 92,175003 (2004)]), ions are dominantly accelerated from ultrathin foils by the radiation pressure and have monoenergetic spectra. In this regime, ions accelerated from the hole-boring process quickly catch up with the ions accelerated by target normal sheath acceleration, and they then join in a single bunch, undergoing a hybrid light-sail-target normal sheath acceleration. Under an appropriate coupling condition between foil thickness, laser intensity, and pulse duration, laser radiation pressure can be dominant in this hybrid acceleration. Two-dimensional particle-in-cell simulations show that 1.26 GeV quasimonoenergetic C6+ beams are obtained by linearly polarized laser pulses at intensities of 1021 W cm-2. [ABSTRACT FROM AUTHOR]

Levy flights constitute a broad class of random walks that occur in many fields of research, from biology to economy and geophysics. The recent advent of Levy glasses allows us to study Levy flights-- and the resultant superdiffusion--using light waves. This raises several questions about the influence of interference on superdiffusive transport. Superdiffusive structures have the extraordinary property that all points are connected via direct jumps, which is expected to have a strong impact on interference effects such as weak and strong localization. Here we report on the experimental observation of weak localization in Levy glasses and compare our results with a recently developed theory for multiple scattering in superdiffusive media. Experimental results are in good agreement with theory and allow us to unveil the light propagation inside a finite-size superdiffusive system. [ABSTRACT FROM AUTHOR]

Coupled-channel effects due to coupling of charmonia to the charmed and anticharmed mesons are of current interest in heavy quarkonium physics. However, the effects have not been unambiguously established. In this Letter, a clean method is proposed in order to examine the coupled-channel effects in charmonium transitions. We show that the hindered M1 radiative transitions from the IP to IP charmonia are suitable for this purpose. We suggest to measure one or more of the ratios &Ggr;(h'c → Xcjγ)/&Ggr;(x'cj → XcjΠ0) and &Ggr;(x'cj → XcjΠ)/&Ggr;(x'cj → XcjΠ0), for which highly nontrivial and parameter-free predictions are given. The picture can also be tested using both unquenched and quenched lattice calculations. [ABSTRACT FROM AUTHOR]

We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from 208Pb. APV is sensitive to the radius of the neutron distribution (Rn). The result Apv = 0.656 ± 0.060(stat) ± 0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions Rn -- Rp = 0.33+0.16-0.18 fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus. [ABSTRACT FROM AUTHOR]

We report on a new approach to the calculation of Chern-Simons theory expectation values, using the mathematical underpinnings of loop quantum gravity, as well as the Duflo map, a quantization map for functions on Lie algebras. These new developments can be used in the quantum theory for certain types of black hole horizons, and they may offer new insights for loop quantum gravity, Chern-Simons theory and the theory of quantum groups. [ABSTRACT FROM AUTHOR]

We compute the universal generic corrections to the inflationary power spectrum due to unknown high-energy physics. We arrive at this result via a careful integrating out of massive fields in the "in-in" formalism yielding a consistent and predictive low-energy effective description in time-dependent backgrounds. We find that the power spectrum is universally modified, order H/M, where H is the scale of inflation. This is qualitatively different from the universal corrections in time-independent backgrounds, and it suggests that such effects may be present in upcoming cosmological observations. [ABSTRACT FROM AUTHOR]

An isolated quantum many-body system in an initial pure state will come to thermal equilibrium if it satisfies the eigenstate thermalization hypothesis (ETH). We consider alternatives to ETH that have been proposed. We first show that von Neumann's quantum ergodic theorem relies on an assumption that is essentially equivalent to ETH. We also investigate whether, following a sudden quench, special classes of pure states can lead to thermal behavior in systems that do not obey ETH, namely, integrable systems. We find examples of this, but only for initial states that obeyed ETH before the quench. [ABSTRACT FROM AUTHOR]

We present a measurement of the time-dependent CP-violating asymmetry in Bos → J/ ψ &phgr; decays, using data collected with the LHCb detector at the LHC. The decay time distribution of Bos → J/ ψ &phgr; is characterized by the decay widths ГH and ГL of the heavy and light mass eigenstates, respectively, of the Bos - B¯os system and by a CP-violating phase &phgr;s. In a sample of about 8500 Bos → J/ ψ &phgr; events isolated from 0.37 fb-1 of pp collisions at √s = 7 TeV, we measure &phgr;s = 0.15 ± 0.18(stat) ± 0.06(syst) rad. We also find an average Bos → decay width Гs c (Г + ГL;H)/2 = 0.657 ± 0.009(stat) ± 0.008(syst) ps-1 and a decay width difference Δ ≡ ГL-ГH = 0.123 ± 0.029(stat) ± 0.011 (syst) ps-1. Our measurement is insensitive to the transformation (&phgr;s, ΔГs) ↦ (&pgr; -- &phgr;s, -- ΔГs). [ABSTRACT FROM AUTHOR]

The propagation of elastic waves in a box under direct shear, filled with glass beads and being sheared at constant rates, is studied experimentally and theoretically. The respective velocities are shown to be essentially unchanged from that in a static granular system under the same pressure and shear stress but without a shear band. Influence of shear band on sound behaviors are also briefly discussed. [ABSTRACT FROM AUTHOR]

Diffusive properties of a monodisperse system of interacting particles confined to a quasi-one-dimensional channel are studied using molecular dynamics simulations. We calculate numerically the mean-squared displacement (MSD) and investigate the influence of the width of the channel (or the strength of the confinement potential) on diffusion in finite-size channels of different shapes (i.e., straight and circular). The transition from single-file diffusion to the two-dimensional diffusion regime is investigated. This transition [regarding the calculation of the scaling exponent (&agr;) of the MSD (&Dgr;x2(t)) ∝ t&agr;] as a function of the width of the channel is shown to change depending on the channel's confinement profile. In particular, the transition can be either smooth (i.e., for a parabolic confinement potential) or rather sharp (i.e., for a hard-wall potential), as distinct from infinite channels where this transition is abrupt. This result can be explained by qualitatively different distributions of the particle density for the different confinement potentials. [ABSTRACT FROM AUTHOR]

In this paper, we study many geometrical properties of contour loops to characterize the morphology of synthetic multifractal rough surfaces, which are generated by multiplicative hierarchical cascading processes. To this end, two different classes of multifractal rough surfaces are numerically simulated. As the first group, singular measure multifractal rough surfaces are generated by using the p model. The smoothened multifractal rough surface then is simulated by convolving the first group with a so-called Hurst exponent, H*. The generalized multifractal dimension of isoheight lines (contours), D(q), correlation exponent of contours, xl, cumulative distributions of areas, &xgr;, and perimeters, n, are calculated for both synthetic multifractal rough surfaces. Our results show that for both mentioned classes, hyperscaling relations for contour loops are the same as that of monofractal systems. In contrast to singular measure multifractal rough surfaces, H* plays a leading role in smoothened multifractal rough surfaces. All computed geometrical exponents for the first class depend not only on its Hurst exponent but also on the set of p values. But in spite of multifractal nature of smoothened surfaces (second class), the corresponding geometrical exponents are controlled by H*, the same as what happens for monofractal rough surfaces. [ABSTRACT FROM AUTHOR]

Diffusion coefficients are intrinsically random in subdiffusion attributable to power-law trapping. Using deterministic biased and unbiased diffusion models, we investigate the Einstein relation for single trajectories in subdiffusion. The difference in the generalized Lyapunov exponent between biased and unbiased deterministic diffusions is related to the velocity under a bias. By Hopfs ergodic theorem, the ratios between the velocities and the Lyapunov exponents for single trajectories converge to a universal constant, which is proportional to the strength of the bias. Based on a certain transport coefficient obtained from a single trajectory, we provide a relation for the transport coefficients divided by the Lyapunov exponent and generalize the Einstein relation for single trajectories. [ABSTRACT FROM AUTHOR]

We study theoretically the effect of the variation of the elastic constants on the stability of cholesteric blue phases (BPs). We demonstrate that the stability of BPs is greatly enhanced when the bend elastic constant Ä33 is smaller, in agreement with recent experimental findings. Larger splay (K11) and twist (K22) elastic constants also stabilize BPs. Our argument sheds light on the subtle effect of the variation of the elastic constants on the stability of BPs, and could guide the synthesis of liquid crystals with a wider temperature range of stable BPs. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated kinetic processes in a two-dimensional turbulent plasma using direct numerical simulations of a hybrid Vlasov-Maxwell model. The link between spatial magnetic structures, such as magnetic vortices and the formation of non-Maxwellian features is investigated. It also presents the statistical description of the link between the magnetic skeleton of turbulence and velocity subspace of the distribution function (DF).

The article reports on the discovery of a new type of coherent structure, a shock ageostrophic modon, that exists in a rotating shallow water model at large Rossby numbers. This structure is essentially asymmetric, preserves coherence for a longtime, and moves along a circular path. It is long living, with a stationary hydraulic jump.

The article discusses a direct numerical simulation of the Blasius boundary-layer flow to track the dynamics in the region of phase space separating transitional from relaminarizing trajectories. It demonstrates how the corresponding disturbance is fully localized and spreads slowly in space. Using dynamical rescaling with the local boundary-layer thickness, a quasicyclic mechanism for the generation of offspring is also unfolded.

The article discusses a study which used numerical approach and found that blackbody friction on atoms either in dilute environments or in hot ovens is larger than previously thought by orders of magnitude. It demonstrates how far off-resonant driving of transitions by low-frequency thermal radiation leads to this enhancement. The study also found that at typical temperatures, the blackbody radiation maximum lies far below the atomic transition wavelength.

The article discusses an alternative strategy for creating Trojan wave packets that utilizes linearly polarized fields. It aims to show that far superior stabilization can be achieved by driving with a linearly polarized sinusoidal field whose frequency is resonant with the wave packet and whose phase is synchronized with its orbital phase. Monte Carlo simulations show that the protocol is remarkably efficient with over 80% of the initial atoms being transferred to the higher n states.

The article employs symmetries or other model assignments to show that phenomenological consequences of residual symmetries ℤS2 (k) and ℤS2 (k) can be readily established, predicting not only θ x to be large, fitting the T2K, MINOS, and Double Chooz data, but also ( ) nearly maximal in good agreement with the latest global fits. A distribution for the leptonic Jarlskog invariant Jv is also given.

The article presents exact analytical results for the order statistics and the gap distribution of a time series where x m represents the position of a random walker at discrete time m. The results found a rather rich and universal behavior independent of the details of the jump distribution. The results also present an interesting and useful example of solvable order statistics in a correlated time series.

The anomalous conformai transformation law of the generalized entropy is found for dilaton gravity coupled to a 1 + 1 conformai matter sector with central charges c = &ctilde;. (When c ≠ &ctilde; the generalized entropy is not invariant under local Lorentz boosts.) It is shown that a certain second null derivative of the entropy, S″gen + (6/c)(S′oUt)2, is primary, and therefore retains its sign under a general conformai transformation. Consequently, all conformai vacua have increasing entropy on causal horizons. Alternative definitions of the horizon, including apparent or dynamical horizons, can have decreasing entropy in any dimension D≥2. This indicates that the generalized second law should be defined using the causal horizon. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamics of the flapping regime of a filament placed in a two-dimensional soap-film flow for different filament lengths and flow speeds. It was found that the onset of flapping is quasiperiodic, with the main flapping amplitude and frequency modulated by low-amplitude, low-frequency oscillation. At higher flow velocities, the oscillation becomes chaotic. The transition to chaos occurs via the quasiperiodic route to chaos. A new bistability phenomenon was discovered in which the system alternates between the stretched-straight and oscillatory states, which is here referred to as "switching oscillation." Unlike some previously reported forms of bistability, in this case the system alternates between the two states continuously, without any external perturbation. [ABSTRACT FROM AUTHOR]

A coupling phase is deemed to be crucial in stabilizing behavior in nonlinear systems. In this paper, we study how the coupling phase influences the delay-induced oscillation death (OD) in coupled oscillators. The OD boundaries are identified analytically even in the presence of the coupling phase. We find that OD only occurs for a coupling phase belonging to a certain interval. The optimal coupling phase, under which the largest OD island forms, is characterized well by a power law scaling with respect to the frequency. The coupling phase turns out to be a key parameter that determines a delay-induced OD. Furthermore, the controlling role of the coupling phase generally is proved to hold fairly for networked delay-coupled oscillators. [ABSTRACT FROM AUTHOR]

We investigate the existence and stability of traveling-wave solutions in a continuum field of nonlocally coupled identical phase oscillators with distance-dependent propagation delays. A comprehensive stability diagram in the parametric space of the system is presented that shows a rich structure of multistable regions and illuminates the relative influences of time delay, the nonlocality parameter and the intrinsic oscillator frequency on the dynamics of these states. A decrease in the intrinsic oscillator frequency leads to a break-up of the stability domains of the traveling waves into disconnected regions in the parametric space. These regions exhibit a tongue structure for high connectivity, whereas they submerge into the stable region of the synchronous state for low connectivity. One finding is the existence of forbidden regions in the parametric space where no phase-locked solutions are possible. We also discover a new class of nonstationary breather states for this model system that are characterized by periodic oscillations of the complex order parameter. [ABSTRACT FROM AUTHOR]

Robustness of two coupled networks systems has been studied separately only for dependency coupling [Buldyrev et al., Nature (London) 464, 1025 (2010)] and only for connectivity coupling [Leicht and D'Souza, e-print arXiv:0907.0894], Here we study, using a percolation approach, a more realistic coupled networks system where both interdependent and interconnected links exist. We find rich and unusual phase-transition phenomena including hybrid transition of mixed first and second order, i.e., discontinuities like in a first-order transition of the giant component followed by a continuous decrease to zero like in a second-order transition. Moreover, we find unusual discontinuous changes from second-order to first-order transition as a function of the dependency coupling between the two networks. [ABSTRACT FROM AUTHOR]

Quasiballistic heat transfer occurs when there is a temperature gradient over length scales comparable to phonon mean free paths (MFPs). This regime has been of interest recently because observation of quasiballistic transport can lead to useful information about phonon MFPs, knowledge of which is essential for engineering nanoscale thermal effects. Here, we use the Boltzmann transport equation (BTE) to understand how observations of quasiballistic transport can yield information about MFPs. We solve the transient, one-dimensional, frequency-dependent BTE for a double-layer structure of a metal film on a substrate, the same geometry that is used in transient thermoreflectance experiments, using a frequency-dependent interface condition. Our results indicate that phonons with MFPs longer than the thermal penetration depth do not contribute to the measured thermal conductivity, providing a means to probe the MFP distribution. We discuss discrepancies between our simulation and experimental observations which offer opportunities for future investigation. [ABSTRACT FROM AUTHOR]

The geometrical effect of a two-dimensional electron gas system with the Rashba and Dresselhaus spin-orbital interactions on a curved surface is studied; it corresponds to a non-Abelian gauge field and a scalar field. The behavior of electrons with spin on a curved space can be transformed into that of a simple system of an electron with spin on a flat surface with a geometrical metric tensor. In addition to the dynamic phase of traveling electrons on a flat surface, a geometrical phase induced by curved space is also observed, and this phase can be demonstrated by use of the path integral. Therefore, the spin-rotation operator and quantum loop of electrons with spin on a curved space are obtained. The induced phases on three curved spaces with flat, cylindrical, and spherical geometry are calculated, and the roles of space curvature in spin precession are also analyzed. [ABSTRACT FROM AUTHOR]

We investigate the aggregation kinetics of a simulated telechelic polymer gel. In the hybrid molecular dynamics (MD)/Monte Carlo (MC) algorithm, aggregates of associating end groups form and break according to MC rules, while the position of the polymers in space is dictated by MD. As a result, the aggregate sizes change over time. In order to describe this aggregation process, we employ master equations. They define changes in the number of aggregates of a certain size in terms of reaction rates. These reaction rates indicate the likelihood that two aggregates combine to form a large one, or that a large aggregate splits into two smaller parts. The reaction rates are obtained from the simulations for a range of temperatures. Our results indicate that the rates are not only temperature dependent, but also a function of the sizes of the aggregates involved in the reaction. Using the measured rates, solutions to the master equations are shown to be stable and in agreement with the aggregate size distribution, as obtained directly from simulation data. Furthermore, we show how temperature-induced variations in these rates give rise to the observed changes in the aggregate distribution that characterizes the sol-gel transition. [ABSTRACT FROM AUTHOR]

The nonlinear dynamics of a nonisothermal thin liquid film on a horizontal cylindrical surface subjected to axial harmonic vibration is investigated in this paper. It is found that the capillary instability of an axisymmetric film on a still cylinder can be saturated via the Marangoni effect by heating the film at the gas side, similar to the saturation of the Rayleigh-Taylor instability in the planar case. If the capillary instability is not saturated by the Marangoni effect, the combined capillary-Marangoni instability can be saturated by the harmonic axial forcing provided that the forcing amplitude exceeds a certain critical value depending on the rest of parameters. The critical amplitude is demonstrated to increase with the Marangoni number when other parameters are fixed. The critical forcing amplitude at a given forcing frequency is shown to be well approximated by a piecewise linear function of the Marangoni number. [ABSTRACT FROM AUTHOR]

When a voltage is applied across a thin layer of cholesteric liquid crystal, fingers of cholesteric alignment can form and propagate in the layer. In computer simulation, based on experimental laboratory results, we demonstrate that these cholesteric fingers can solve selected problems of computational geometry, logic, and arithmetics. We show that branching fingers approximate a planar Voronoi diagram, and nonbranching fingers produce a convex subdivision of concave polygons. We also provide a detailed blueprint and simulation of a one-bit half-adder functioning on the principles of collision-based computing, where the implementation is via collision of liquid crystal fingers with obstacles and other fingers. [ABSTRACT FROM AUTHOR]

A three-dimensional symmetric binary fluid is studied, as a function of temperature, in the two-phase (liquid-liquid) coexistence region via Monte Carlo simulations. Particular focus has been in the understanding of curvature-dependent interfacial tension, which is observed to vary as &sgr;(R) = &sgr;(∞)/[1 +2(£/R)2|, implying that a Tolman length is zero in the limit R → &∞;. The length ℓ is found to have a critical divergence the same as the correlation length, but its amplitude is significantly larger (ℓ ⋍ 4&xgr;). Our findings hence imply that the barrier against homogeneous nucleation is significantly reduced (in comparison with the classical nucleation theory) in the critical region. We also report results for the critical behavior of the flat interfacial tension &sgr;(∞) and the concentration susceptibility, as well as the amplitude ratios involving these thermodynamic quantities. Noting that the interatomic potential in our model is described by the Lennard-Jones form that decays faster that 1/r3, all of our results for critical phenomena are expectedly consistent with the Ising universality class of three spatial dimensions. [ABSTRACT FROM AUTHOR]

We consider a nanodimer in solution with asymmetric thermal properties that shows self-propelled motion. One monomer of the nanodimer can be heated to a fixed temperature producing a radially symmetric temperature gradient. The thermophoretic properties of the second monomer produce then a propulsion against or toward the heated particle, such that the nanodimer becomes a puller or pusher nanoswimmer. We combine our simulation measurements with a theoretical analysis that satisfactorily characterizes the self-propelled velocity with the temperature gradient, and the thermophoretic properties of the bead. [ABSTRACT FROM AUTHOR]

We reexamine the convolution approximation commonly used in the mode-coupling theory (MCT) of nonergodic states of classical fluids. This approximation concerns the static correlation functions used as input in the MCT treatment of the dynamics. Besides the hard-sphere model, we consider interaction potentials that present a short-range tail, either attractive or repulsive, beyond the hard core. By using accurate static correlation functions obtained from the fundamental measures functional for hard spheres, we show that the role of three-body direct correlations can be more significant than what is inferred from previous simple ansatzs for pure hard spheres. This may in particular impact the location of the glass transition line and the nonergodicity parameter. [ABSTRACT FROM AUTHOR]

The elastocapillary instability of a flexible plate plunged in a liquid bath is analyzed theoretically. We show that the plate can bend due to two separate destabilizing mechanisms, when the liquid is partially wetting the solid. For contact angles &thgr;e > π/2, the capillary forces acting tangential to the surface are compressing the plate and can induce a classical buckling instability. However, a second mechanism appears due to capillary forces normal to surface. These induce a destabilizing torque that tends to bend the plate for any value of the contact angle &thgr;e > 0. We denote these mechanisms as "buckling" and "bending," respectively and identify the two corresponding dimensionless parameters that govern the elastocapillary stability. The onset of instability is determined analytically and the different bifurcation scenarios are worked out for experimentally relevant conditions. [ABSTRACT FROM AUTHOR]

We report a detailed study, using state-of-the-art simulation and theoretical methods, of the effective (depletion) potential between a pair of big hard spheres immersed in a reservoir of much smaller hard spheres, the size disparity being measured by the ratio of diameters q ≡ &sgr;s/&sgr;b. Small particles are treated grand canonically. their influence being parameterized in terms of their packing fraction in the reservoir &eegr;rs. Two Monte Carlo simulation schemes-the geometrical cluster algorithm, and staged particle insertion-are deployed to obtain accurate depletion potentials for a number of combinations of q ≼ 0.1 and. After applying corrections for simulation finite-size effects, the depletion potentials are compared with the prediction of new density functional theory (DFT) calculations based on the insertion trick using the Rosenfeld functional and several subsequent modifications. While agreement between the DFT and simulation is generally good, significant discrepancies are evident at the largest reservoir packing fraction accessible to our simulation methods, namely, &eegr;rs = 0.35. These discrepancies are, however, small compared to those between simulation and the much poorer predictions of the Derjaguin approximation at this &eegr;rs. The recently proposed morphometric approximation performs better than Derjaguin but is somewhat poorer than DFT for the size ratios and small-sphere packing fractions that we consider. The effective potentials from simulation, DFT, and the morphometric approximation were used to compute the second virial coefficient B2 as a function of &eegr;rs. Comparison of the results enables an assessment of the extent to which DFT can be expected to correctly predict the propensity toward fluid-fluid phase separation in additive binary hard-sphere mixtures with q ≼ 0.1. In all, the new simulation results provide a fully quantitative benchmark for assessing the relative accuracy of theoretical approaches for calculating depletion potentials in highly size-asymmetric mixtures. [ABSTRACT FROM AUTHOR]

Long-lived quasistationary states, associated with stationary stable solutions of the Vlasov equation, are found in systems with long-range interactions. Studies of the relaxation time in a model of N globally coupled particles moving on a ring, the Hamiltonian mean-field model (HMF), have shown that it diverges as NY for large N, with &ggr; -≃1-7 for some initial conditions with homogeneously distributed particles. We propose a method for identifying exact inhomogeneous steady states in the thermodynamic limit, based on analyzing models of uncoupled particles moving in an external field. For the HMF model, we show numerically that the relaxation time of these states diverges with N&ggr; with the exponent &ggr; ≃ 1. The method, applicable to other models with globally coupled particles, also allows an exact evaluation of the stability I imit of homogeneous steady states. In some cases, it provides a good approximation for the correspondence between the initial condition and the final steady state. [ABSTRACT FROM AUTHOR]

Salt transport in bulk electrolytes is limited by diffusion and advection, but in microstructures with charged surfaces (e.g., microfluidic devices, porous media, soils, or biological tissues) surface conduction and electro-osmotic flow also contribute to ionic fluxes. For small applied voltages, these effects lead to well known linear electrokinetic phenomena. In this paper, we predict some surprising nonlinear dynamics that can result from the competition between bulk and interfacial transport at higher voltages. When counterions are selectively removed by a membrane or electrode, a "deionization shock" can propagate through the microstructure, leaving in its wake an ultrapure solution, nearly devoid of coions and colloidal impurities. We elucidate the basic physics of deionization shocks and develop a mathematical theory of their existence, structure, and stability, allowing for slow variations in surface charge or channel geometry. Via asymptotic approximations and similarity solutions, we show that deionization shocks accelerate and sharpen in narrowing channels, while they decelerate and weaken, and sometimes disappear, in widening channels. These phenomena may find applications in separations (deionization, decontamination, biological assays) and energy storage (batteries, supercapacitors) involving electrolytes in microstructures. [ABSTRACT FROM AUTHOR]

We report on the dynamics of a model frictional system submitted to minute external perturbations. The system consists of a chain of sliders connected through elastic springs that rest on an incline. By introducing cyclic expansions and contractions of the springs we observe a reptation of the chain. We account for the average reptation velocity theoretically. The velocity of small systems exhibits a series of plateaus as a function of the incline angle. Due to elastic effects, there exists a critical amplitude below which the reptation is expected to cease. However, rather than a full stop of the creep, we observe in numerical simulations a transition between a continuous-creep and an irregular-creep regime when the critical amplitude is approached. The latter transition is reminiscent of the transition between the continuous and the irregular compaction of granular matter submitted to periodic temperature changes. [ABSTRACT FROM AUTHOR]

This paper investigates the lift force exerted on an elliptical obstacle immersed in a granular flow through analytical calculations and computer simulations. The results are shown as a function of the obstacle si/e. orientation with respect to the flow direction (tilt angle), the restitution coefficient and ellipse eccentricity. The theoretical argument, based on the force exerted on the obstacle due to inelastic, frictionless collisions of a very dilute flow, captures the qualitative features of the lift, but fails to reproduce the data quantitatively. The reason behind this disagreement is that the dilute flow assumption on which this argument is built breaks down as a granular shock wave forms in front of the obstacle. More specifically, the shock wave changes the grains impact velocity at the obstacle, decreasing the overall net lift obtained from a very dilute flow. [ABSTRACT FROM AUTHOR]

We determine the complexity of several constraint satisfaction problems using the quantum adiabatic algorithm in its simplest implementation. We do so by studying the size dependence of the gap to the first excited state of "typical" instances. We find that, at large sizes N, the complexity increases exponentially for all models that we study. We also compare our results against the complexity of the analogous classical algorithm WalkSAT and show that the harder the problem is for the classical algorithm, the harder it is also for the quantum adiabatic algorithm. [ABSTRACT FROM AUTHOR]

Game-theoretical models where the rules of the game and the interaction structure both coevolve with the game dynamics-multiadaptive games-capture very flexible situations where cooperation among selfish agents can emerge. In this work, we will discuss a multiadaptive model presented in a recent Letter [Phys. Rev. Lett. 106, 028702 (2011)] as well as generalizations of it. The model captures a nonequilibrium situation where social unrest increases the incentive to cooperate and, simultaneously, agents are partly free to influence with whom they interact. First, we investigate the details of how feedback from the behavior of agents determines the emergence of cooperation and hierarchical contact structures. We also study the stability of the system to different types of noise, and find that different regions of parameter space show very different response. Some types of noise can destroy an all-cooperator (C) state. If, on the other hand, hubs are stable, then so is the all-C state. Finally, we investigate the dependence of the ratio between the time scales of strategy updates and the evolution of the interaction structure. We find that a comparatively fast strategy dynamics is a prerequisite for the emergence of cooperation. [ABSTRACT FROM AUTHOR]

For a broad class of random walks with anisotropic scattering kernels and absorption, we derive explicit formulas that allow expressing the moments of the collision number nv performed in a volume V as a function of the particle equilibrium distribution. Our results apply to arbitrary domains V and boundary conditions, and allow assessing the hitting statistics for systems where the typical displacements are comparable to the domain size, so that the diffusion limit is possibly not attained. An example is discussed for one-dimensional random flights with exponential displacements, where analytical calculations can be carried out. [ABSTRACT FROM AUTHOR]