@article{BaibolatovRosenblumZhanabaevetal.2010,
  author    = {Baibolatov, Yernur and Rosenblum, Michael and Zhanabaev, Zeinulla Zh. and Pikovskij, Arkadij},
  title     = {Complex dynamics of an oscillator ensemble with uniformly distributed natural frequencies and global nonlinear coupling},
  issn      = {1539-3755},
  doi       = {10.1103/Physreve.82.016212},
  year      = {2010},
  abstract  = {We consider large populations of phase oscillators with global nonlinear coupling. For identical oscillators such populations are known to demonstrate a transition from completely synchronized state to the state of self-organized quasiperiodicity. In this state phases of all units differ, yet the population is not completely incoherent but produces a nonzero mean field; the frequency of the latter differs from the frequency of individual units. Here we analyze the dynamics of such populations in case of uniformly distributed natural frequencies. We demonstrate numerically and describe theoretically (i) states of complete synchrony, (ii) regimes with coexistence of a synchronous cluster and a drifting subpopulation, and (iii) self-organized quasiperiodic states with nonzero mean field and all oscillators drifting with respect to it. We analyze transitions between different states with the increase of the coupling strength; in particular we show that the mean field arises via a discontinuous transition. For a further illustration we compare the results for the nonlinear model with those for the Kuramoto-Sakaguchi model.},
  language  = {en}
}
@article{BalažVidanovicBogojevićetal.2010,
  author    = {Balaž, Antun and Vidanovic, Ivana and Bogojević, Aleksandar and Pelster, Axel},
  title     = {Ultra-fast converging path-integral approach for rotating ideal Bose-Einstein condensates},
  issn      = {0375-9601},
  doi       = {10.1016/j.physleta.2010.01.034},
  year      = {2010},
  abstract  = {A recently developed efficient recursive approach for analytically calculating the short-time evolution of the one-particle propagator to extremely high orders is applied here for numerically studying the thermodynamical and dynamical properties of a rotating ideal Bose gas of Rb-87 atoms in an anharmonic trap. At first, the one-particle energy spectrum of the system is obtained by diagonalizing the discretized short-time propagator. Using this, many-boson properties such as the condensation temperature, the ground-state occupancy, density profiles, and time-of-flight absorption pictures are calculated for varying rotation frequencies. The obtained results improve previous semiclassical calculations, in particular for smaller particle numbers. Furthermore, we find that typical time scales for a free expansion are increased by an order of magnitude for the delicate regime of both critical and overcritical rotation.},
  language  = {en}
}
@article{BangeSchubertNeher2010,
  author    = {Bange, Sebastian and Schubert, Marcel and Neher, Dieter},
  title     = {Charge mobility determination by current extraction under linear increasing voltages : case of nonequilibrium charges and field-dependent mobilities},
  issn      = {1098-0121},
  doi       = {10.1103/Physrevb.81.035209},
  year      = {2010},
  abstract  = {The method of current extraction under linear increasing voltages (CELIV) allows for the simultaneous determination of charge mobilities and charge densities directly in thin-film geometries as used in organic photovoltaic (OPV) cells. It has been specifically applied to investigate the interrelation of microstructure and charge-transport properties in such systems. Numerical and analytical calculations presented in this work show that the evaluation of CELIV transients with the commonly used analysis scheme is error prone once charge recombination and, possibly, field- dependent charge mobilities are taken into account. The most important effects are an apparent time dependence of charge mobilities and errors in the determined field dependencies. Our results implicate that reports on time-dependent mobility relaxation in OPV materials obtained by the CELIV technique should be carefully revisited and confirmed by other measurement methods.},
  language  = {en}
}
@article{BarthelKlieschEisert2010,
  author    = {Barthel, Thomas and Kliesch, Martin and Eisert, Jens},
  title     = {Real-space renormalization yields finite correlations},
  issn      = {0031-9007},
  doi       = {10.1103/Physrevlett.105.010502},
  year      = {2010},
  abstract  = {Real-space renormalization approaches for quantum lattice systems generate certain hierarchical classes of states that are subsumed by the multiscale entanglement renormalization Ansatz (MERA). It is shown that, with the exception of one spatial dimension, MERA states are actually states with finite correlations, i.e., projected entangled pair states (PEPS) with a bond dimension independent of the system size. Hence, real-space renormalization generates states which can be encoded with local effective degrees of freedom, and MERA states form an efficiently contractible class of PEPS that obey the area law for the entanglement entropy. It is further pointed out that there exist other efficiently contractible schemes violating the area law.},
  language  = {en}
}
@article{BimonteHaakhHenkeletal.2010,
  author    = {Bimonte, Giuseppe and Haakh, Harald Richard and Henkel, Carsten and Intravaia, Francesco},
  title     = {Optical BCS conductivity at imaginary frequencies and dispersion energies of superconductors},
  issn      = {1751-8113},
  doi       = {10.1088/1751-8113/43/14/145304},
  year      = {2010},
  abstract  = {We present an efficient expression for the analytic continuation to arbitrary complex frequencies of the complex optical and ac conductivity of a homogeneous superconductor with an arbitrary mean free path. Knowledge of this quantity is fundamental in the calculation of thermodynamic potentials and dispersion energies involving type-I superconducting bodies. When considered for imaginary frequencies, our formula evaluates faster than previous schemes involving Kramers-Kronig transforms. A number of applications illustrate its efficiency: a simplified low-frequency expansion of the conductivity, the electromagnetic bulk self-energy due to longitudinal plasma oscillations, and the Casimir free energy of a superconducting cavity.},
  language  = {en}
}
@article{BlakesleyClubbGreenham2010,
  author    = {Blakesley, James C. and Clubb, Helen S. and Greenham, Neil C.},
  title     = {Temperature-dependent electron and hole transport in disordered semiconducting polymers : analysis of energetic disorder},
  issn      = {1098-0121},
  doi       = {10.1103/Physrevb.81.045210},
  year      = {2010},
  abstract  = {We have used space-charge limited current measurements to study the mobility of holes and electrons in two fluorene-based copolymers for temperatures from 100 to 300 K. Interpreting the results using the standard analytical model produced an Arrhenius-type temperature dependence for a limited temperature range only and mobility was found to be apparently dependent on the thickness of the polymer film. To improve on this, we have interpreted our data using a numerical model that takes into account the effects of the carrier concentration and energetic disorder on transport. This accounted for the thickness dependence and gave a more consistent temperature dependence across the full range of temperatures, giving support to the extended Gaussian disorder model for transport in disordered polymers. Furthermore, we find that the same model adequately describes both electron and hole transport without the need to explicitly include a distribution of electron traps. Room-temperature mobilities were found to be in the region of 4 x 10(-8) and 2 x 10(- 8) cm(2) V-1 s(-1) in the limit of zero field and zero carrier density with disorders of 110+/-10 and 100+/-10 meV for polymers poly{9,9-dioctylfluorene-co-bis[N,N'-(4-butylphenyl)]bis(N, N'-phenyl-1,4-phenylene)diamine} and poly(9,9-dioctylfluorene-co-benzothiadiazole), respectively.},
  language  = {en}
}
@article{BoedekerBetaFranketal.2010,
  author    = {Boedeker, Hendrik Ulrich and Beta, Carsten and Frank, Till D. and Bodenschatz, Eberhard},
  title     = {Quantitative analysis of random ameboid motion},
  issn      = {0295-5075},
  doi       = {10.1209/0295-5075/90/28005},
  year      = {2010},
  abstract  = {We quantify random migration of the social ameba Dictyostelium discoideum. We demonstrate that the statistics of cell motion can be described by an underlying Langevin-type stochastic differential equation. An analytic expression for the velocity distribution function is derived. The separation into deterministic and stochastic parts of the movement shows that the cells undergo a damped motion with multiplicative noise. Both contributions to the dynamics display a distinct response to external physiological stimuli. The deterministic component depends on the developmental state and ambient levels of signaling substances, while the stochastic part does not.},
  language  = {en}
}
@article{BordyugovFischerEngeletal.2010,
  author    = {Bordyugov, Grigory and Fischer, Nils and Engel, Harald and Manz, Niklas and Steinbock, Oliver},
  title     = {Anomalous dispersion in the Belousov-Zhabotinsky reaction : experiments and modeling},
  issn      = {0167-2789},
  doi       = {10.1016/j.physd.2009.10.022},
  year      = {2010},
  abstract  = {We report results on dispersion relations and instabilities of traveling waves in excitable systems. Experiments employ solutions of the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction confined to thin capillary tubes which create a pseudo-one-dimensional system. Theoretical analyses focus on a three-variable reaction-diffusion model that is known to reproduce qualitatively many of the experimentally observed dynamics. Using continuation methods, we show that the transition from normal, monotonic to anomalous, single-overshoot dispersion curves is due to an orbit flip bifurcation of the solitary pulse homoclinics. In the case of "wave stacking", this anomaly induces attractive pulse interaction, slow solitary pulses, and faster wave trains. For "wave merging", wave trains break up in the wake of the slow solitary pulse due to an instability of wave trains at small wavelength. A third case, "wave tracking" is characterized by the non-existence of solitary waves but existence of periodic wave trains. The corresponding dispersion curve is a closed curve covering a finite band of wavelengths.},
  language  = {en}
}
@article{BordyugovPikovskijRosenblum2010,
  author    = {Bordyugov, Grigory and Pikovskij, Arkadij and Rosenblum, Michael},
  title     = {Self-emerging and turbulent chimeras in oscillator chains},
  issn      = {1539-3755},
  doi       = {10.1103/Physreve.82.035205},
  year      = {2010},
  abstract  = {We report on a self-emerging chimera state in a homogeneous chain of nonlocally and nonlinearly coupled oscillators. This chimera, i.e., a state with coexisting regions of complete and partial synchrony, emerges via a supercritical bifurcation from a homogeneous state. We develop a theory of chimera based on the Ott-Antonsen equations for the local complex order parameter. Applying a numerical linear stability analysis, we also describe the instability of the chimera and transition to phase turbulence with persistent patches of synchrony.},
  language  = {en}
}
@article{BornLevermann2010,
  author    = {Born, Andreas and Levermann, Anders},
  title     = {The 8.2 ka event : abrupt transition of the subpolar gyre toward a modern North Atlantic circulation},
  issn      = {1525-2027},
  doi       = {10.1029/2009gc003024},
  year      = {2010},
  abstract  = {Climate model simulations of the 8.2 ka event show an abrupt strengthening of the Atlantic subpolar gyre that allows us to connect two major but apparently contradictory climate events of the early Holocene: the freshwater outburst from proglacial lakes and the onset of Labrador Sea water formation. The 8.2 ka event is the largest climatic signal of our present interglacial with a widespread cooling in the North Atlantic region about 8200 years before present. It coincides with a meltwater outburst from North American proglacial lakes that is believed to have weakened the Atlantic meridional overturning circulation and northward heat transport, followed by a recovery of the deep ocean circulation and rising temperatures after a few centuries. Marine proxy data, however, date the onset of deep water formation in Labrador Sea to the same time. The subsequent strengthening of the slope current system created a regional signal recorded as an abrupt and persistent surface temperature decrease. Although similarities in timing are compelling, a mechanism to reconcile these apparently contradictory events was missing. Our simulations show that an abrupt and persistent strengthening of the Atlantic subpolar gyre provides a plausible explanation. The intense freshwater pulse triggered a transition of the gyre circulation into a different mode of operation, stabilized by internal feedbacks and persistent after the cessation of the perturbation. As a direct consequence, deep water formation around its center intensifies. This corresponds to the modern flow regime and stabilizes the meridional overturning circulation, possibly contributing to the Holocene's climatic stability.},
  language  = {en}
}