Universal features of polymer shapes in crowded environments

We study the universal characteristics of the shape of a polymer chain in an environment with correlated structural obstacles, applying the field-theoretical renormalization group approach. Our results qualitatively indicate an increase of the asymmetry of the polymer shape in crowded environment comparing with the pure solution case.     

Polymer translocation in a double-force arrangement

Using Langevin dynamics simulations, we investigate the translocation dynamics of an externally driven polymer chain through a nanopore, where a pulling force F is exerted on the first monomer whilst there is an opposing force F _E < F within the pore. Such a double-force arrangement has been proposed recently to allow better dynamical control of the translocation process in order to sequence biopolymers. We find that in the double-force arrangement translocation becomes slower as compared to the case under a single monomer pulling force of magnitude F - F _E , but scaling of the translocation time as a function of the chain length ∼ N ² does not change. The waiting time (m) for monomer m to exit the pore is found to be a monotonically increasing function of the bead number almost until m N , which indicates relatively well-defined slowing down and control of the chain velocity during translocation. We also study the waiting time distributions for the beads in the chain, and characterize in detail fluctuations in the bead positions and their transverse position coordinates during translocation. These data should be useful in estimating position-dependent sequencing errors in double-force experiments.     

Polymer translocation in the presence of excluded volume and explicit hydrodynamic interactions

Molecular Dynamics simulations of polymer translocation are hereby reported. No external force was applied to the polymer during translocation, and the dynamics was dominated by polymer–pore interactions. It was found that hydrodynamic interactions play an important role in the relaxation of the polymer on each side of the membrane but have a negligible impact on the translocation process itself. Also, the scaling laws obtained for the relaxation and translocation times indicate that long translocating polymers may be considered to be following a quasi-equilibrium anomalous diffusion process in the absence of external forces.     

Polymer translocation through nanopores: Parking lot problems,scaling laws and their breakdown

The passage of a polymer through a narrow pore is associated with the crossing of a significant free energy barrier. Both in nature and in single molecule experiments the polymer is typically driven through the pore. We here address two such driving modes: (i) the driving by binding proteins that prevent (partial) back-sliding through the pore; and (ii) the driving by a trans-membrane force. In case (i) we derive the effective force and show finite size effects due to the size of the binding proteins. In case (ii) we demonstrate the crossover from a slow, equilibrium driving to a non-equilibrium behaviour at fast driving.     

A powerful approach to real-time mobile objects tracking in crowded environments utilizing 3D video analysis of fixed camera,particle filter and neural network

A powerful approach in the area of real-time mobile objects tracking in crowded environments, utilizing 3D video frames analysis is now taken into real consideration, as a candidate to be improved. The method presented here is able to track a number of real-time mobile objects in the real complex situations in the presence of occlusion, overlapping and various shifts. This is a development of probabilistic estimation theory via particle filter. In one such case, the whole of chosen new features of mobile objects, which are unconsidered in the present probabilistic estimation, should first be analyzed through a novel neural network. Subsequently, the probabilistic estimation in each one of frames may be made in a better outcome, as long as all the mentioned components are integrated. Evaluation of the proposed approach through PETS-09 database has been finally carried out, once the results with respect to a number of standard benchmark procedures indicate that 12% accuracy improvement is acquired.     

Autocatalytic reaction dynamics in systems crowded by catalytic obstacles

Reaction and diffusion dynamics in systems crowded by catalytic obstacles are investigated using a particle-based mesoscopic simulation method. The focus of the work is on effects of correlations induced by the presence of the catalytic obstacles and solvent collective modes. As an example, a system is considered where the reaction A+C→B+C takes place on the surfaces of the C catalytic obstacles, while the autocatalytic reaction A+B→2A occurs in the bulk of the solution. It is shown that mean-field, mass-action rate laws break down and fail to describe the reaction dynamics for large volume fractions of obstacles. The influence of hydrodynamics on the reaction and diffusion dynamics is also studied.     

A high accuracy flow segmentation method in crowded scenes based on streakline

Flow segmentation based on similar motion patterns in crowded scenes remains an open problem in computer vision due to inherent complexity and vast diversity found in such scenes. To solve this problem, the streakline framework based on Lagrangian fluid dynamics had been proposed recently. However, this framework computed optical flow field using conventional optical flow method (Lucas Kanade method) which has poor anti-interference performance, and serious deviation would be brought to the computation of optical flow field. Moreover, our experimental results show that using the formulation of streak flow similarity in this framework can result in incorrect flow segmentation. Therefore, we combine this framework with a high accurate variational model, and modify the corresponding formulation of streak flow similarity after analyzing the streakline framework in detail. Finally, an improved method is proposed to solve flow segmentation in crowded scenes. Experiments are done to compare these two methods and results verify the validity and accuracy of our method.     

Protecting entanglement by detuning: in Markovian environments vs in non-Markovian environments

The models of two qubits separately trapped in two independent Markovian or non-Markovian environments have been investigated. The distinction of the two-qubit entanglement dynamics in different environments has also been discussed in detail. The results show that, in non-Markovian environments, the possible usage time of entanglement can be extended due to its memory effect. On the other hand, we note that, compared to Markovian environments, the two-qubit entanglement could be protected better in non-Markovian environments by modulating the detuning between qubits and cavities. Finally, an intuitive physical interpretation for these results is given.     

Electroluminescence of a Polymer Film with a Polymer/Polymer Interface

JETP Letters - The effect of a two-dimensional quantum-confined structure formed at a polymer/polymer interface on the radiative recombination of excitons (i.e., electroluminescence) is...     

Quantum metrology in correlated environments

We analytically obtain the precision bounds of frequency measurements in correlated Markovian and non-Markovian environments using a variational approach. The metrological equivalence of product states and maximally entangled states persisting in maximally correlated Markovian and non-Markovian environments is verified using a standard Ramsey spectroscopy setup. Furthermore, we find that optimal measurements can be used to achieve a much higher resolution than standard Ramsey spectroscopy in correlated environments.     

Quantum correlations in non-Markovian environments

We have studied the analytical Markovian and non-Markovian dynamics of quantum correlations, such as entanglement, quantum discord and Bell nonlocalities for three noisy qubits. Quantum correlation as measured by quantum discord is found to be immune to death contrary to entanglement and Bell nonlocality for initial GHZ- or W-type mixed states.     

Quantum discord in non-Markovian environments

The quantum discord dynamics of two qubits in two independent non-Markovian reservoirs has been investigated. On the condition of resonant interactions, the result shows that the quantum discord has the phenomenon of “revival”. What is more, even in the region where the entanglement is zero, the quantum discord still can reveal the quantum correlations between the two qubits. Considering the detuning, it is interesting to note that the quantum discord can be preserved when the non-Markovian and the detuning conditions are satisfied simultaneously. Finally, an intuitive physical interpretation has been given by the quasimode approach.     

Deterministic walks in random environments

Deterministic walks in random environments (DWRE) occupy an intermediate position between purely random (generated by random trials) and purely deterministic (generated by deterministic dynamical systems, e.g., by maps) models of diffusion. These models combine deterministic and probabilistic features. We review general properties of DWRE and demonstrate that, to a large extent, their dynamics and their statistics can be analyzed consecutively and separately. We also show that orbits of one-dimensional walks in rigid environments with non-constant rigidity almost surely visit each site infinitely many times.     

Diffusion-limited annihilation in inhomogeneous environments

We study diffusion-limited (on-site) pair annihilation A + A → 0 and (on-site) fusion A + A → A which we show to be equivalent for arbitrary space-dependent diffusion and reaction rates. For one-dimensional lattices with nearest neighbour hopping we find that in the limit of infinite reaction rate the time-dependent n-point density correlations for many-particle initial states are determined by the correlation functions of a dual diffusion-limited annihilation process with at most 2n particles initially. Furthermore, by reformulating general properties of annihilating random walks in one dimension in terms of fermionic anticommutation relations we derive an exact representation for these correlation functions in terms of conditional probabilities for a single particle performing a random walk with dual hopping rates. This allows for the exact and explicit calculation of a wide range of universal and non-universal types of behaviour for the decay of the density and density correlations.     

Photoconductivity along the Polymer/Polymer Interface

Physics of the Solid State - The effect of photoexcitation on the electrical conductivity of the interface between two polydiphenylenephthalide (PDP) polymer films is discovered. It is shown that...     

Laser systems in modern production environments

The present situation in production engineering is characterized by a need to create organizational structures and production methods which enable a reduction of the product development time and continuously improved product quality. Together with an improvement in productivity, cost savings and quality assurance, the success of a company will increasingly depend on shortened throughput times, flexibility and the full utilization of its employees' creativity. Laser technology offers important contributions to these aims, if its related technical and organizational advantages can be fully exploited.On an organizational level, the simultaneous development of product, process and production system and multilevel quality control loops enables preventive quality assurance and continuous improvement of product quality. Simulation tools for process, process flow and laser systems allow reliable planning data at a very early stage in product design and operations planning.On the manufacturing level, e.g. in the field of prototype building, the laser is used as a flexible tool for cutting two- and three-dimensional body panels. Owing to the need for programming, the downtimes for 3D laser cutting systems can be quite considerable. Computer-aided, comprehensive process chains enabling off-line programming are therefore increasingly being adopted. The use of the laser in prototype shops makes it possible to provide production-equivalent components at a high level of reproducibility and with much shorter lead times.System status monitoring tools enable full operator control and fast fault rectification. Seam tracking sensors with moving laser beam and moving workpiece allow compensation of tolerances in part shape and position. By measuring the gap distance during seam tracking, suitable adaptation of process parameters makes it possible to achieve a controlled welding process. As a continuation of preventive quality assurance measures, process monitoring using characteristics of the laser-induced plasma during welding reveals defects in the weld seam.     

Directed random walks in random environments

We use holding time methods to study the asymptotic behavior of pure birth processes with random transition rates. Both the normal and slow approaches to infinity are studied. Fluctuations are shown to obey the central limit theorem for almost all sample-transition rates. Our results are stronger, and our proofs simpler, then those of recently published studies.     

Cooperation evolution in random multiplicative environments

Most real life systems have a random component: the multitude of endogenous and exogenous factors influencing them result in stochastic fluctuations of the parameters determining their dynamics. These empirical systems are in many cases subject to noise of multiplicative nature. The special properties of multiplicative noise as opposed to additive noise have been noticed for a long while. Even though apparently and formally the difference between free additive vs. multiplicative random walks consists in just a move from normal to log-normal distributions, in practice the implications are much more far reaching. While in an additive context the emergence and survival of cooperation requires special conditions (especially some level of reward, punishment, reciprocity), we find that in the multiplicative random context the emergence of cooperation is much more natural and effective. We study the various implications of this observation and its applications in various contexts.     

Rings and boxes in dissipative environments

We study a particle on a ring in presence of a dissipative Caldeira-Leggett environment and derive its response to a dc field. We find, through a 2-loop renormalization group analysis, that a large dissipation parameter η flows to a fixed point η(R)=η(c)=?/2π. We also reexamine the mapping of this problem to that of the Coulomb box and show that the relaxation resistance, of recent interest, is quantized for large η. For finite η>η(c) we find that a certain average of the relaxation resistance is quantized. We propose a box experiment to measure a quantized noise.     

Reaction-limited sintering in nearly saturated environments

We study the shape and growth rate of necks between sintered spheres with dissolution–precipitation dynamics in the reaction-limited regime. We determine the critical shape that separates those initial neck shapes that can sinter from those that necessarily dissolve, as well as the asymptotic evolving shape of sinters far from the critical shape. We compare our results with past results for the asymptotic neck shape in closely related but more complicated models of surface dynamics; in particular, we confirm a scaling conjecture, originally due to Kuczinsky. Finally, we consider the relevance of this problem to the diagenesis of sedimentary rocks and other applications.