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Modeling foraging via basic models is a problem that has been recently investigated from several points of view. However, understanding the effect of the spatial distribution of food on the lifetime of a forager has not been achieved yet. We explore here how the distribution of food in space affects the forager's lifetime in several different scenarios. We analyze a random forager and a smelling forager in both one and two dimensions. buy IACS-010759 We first consider a general food distribution, and then analyze in detail specific distributions including constant distance between food, certain probability of existence of food at each site, and power-law distribution of distances between food. For a forager in one dimension without smell we find analytically the lifetime, and for a forager with sense of smell we find the condition for immortality. In two dimensions we find based on analytical considerations that the lifetime (T) scales with the starving time (S) and food density (f) as T∼S^4f^3/2.We investigate the escape of particles from the phase space produced by a two-dimensional, nonlinear and discontinuous, area-contracting map. The mapping, given in action-angle variables, is parametrized by K and γ which control the strength of nonlinearity and dissipation, respectively. We focus on two dynamical regimes, K less then 1 and K≥1, known as slow and quasilinear diffusion regimes, respectively, for the area-preserving version of the map (i.e., when γ=0). When a hole of hight h is introduced in the action axis we find both the histogram of escape times P_E(n) and the survival probability P_S(n) of particles to be scale invariant, with the typical escape time n_typ=exp〈lnn〉; that is, both P_E(n/n_typ) and P_S(n/n_typ) define universal functions. Moreover, for γ≪1, we show that n_typ is proportional to h^2/D, where D is the diffusion coefficient of the corresponding area-preserving map that in turn is proportional to K^5/2 and K^2 in the slow and the quasilinear diffusion regimes, respectively.Understanding the drift motion and dynamical locking of crystalline clusters on patterned substrates is important for the diffusion and manipulation of nano- and microscale objects on surfaces. In a previous work, we studied the orientational and directional locking of colloidal two-dimensional clusters with triangular structure driven across a triangular substrate lattice. Here we show with experiments and simulations that such locking features arise for clusters with arbitrary lattice structure sliding across arbitrary regular substrates. Similar to triangular-triangular contacts, orientational and directional locking are strongly correlated via the real- and reciprocal-space Moiré patterns of the contacting surfaces. Due to the different symmetries of the surfaces in contact, however, the relation between the locking orientation and the locking direction becomes more complicated compared to interfaces composed of identical lattice symmetries. We provide a generalized formalism which describes the relation between the locking orientation and locking direction with arbitrary lattice symmetries.Langevin dynamical simulations of shear-induced melting two-dimensional (2D) dusty plasmas are performed to study the determination of the shear viscosity of this system. It is found that the viscosity calculated from the Green-Kubo relation, after removing the drift motion, well agrees with the viscosity definition, i.e., the ratio of the shear stress to the shear rate in the sheared region, even the shear rate is magnified ten times higher than that in experiments. The behaviors of shear stress and its autocorrelation function of shear-induced melting 2D dusty plasmas are compared with those of uniform liquids at the same temperatures, leading to the conclusion that the Green-Kubo relation is still applicable to determine the viscosity for shear-induced melting dusty plasmas.We present a macroscopic two-fluid model to explain the breakdown of flow alignment in nematic liquid crystals under shear flow due to smectic clusters. We find that the velocity difference of the two fluids plays a key role to mediate the time-dependent behavior as soon as a large enough amount of smectic order is induced by flow. For the minimal model it is sufficient to keep the nematic degrees of freedom, the mass density of the smectic clusters and the degree of smectic order, the density, and two velocities as macroscopic variables. While frequently a smectic A or C phase arises at lower temperatures, this is not required for the applicability of the present model. Indeed, as pointed out before by Gähwiller, there are compounds showing a breakdown of flow alignment over a large temperature range and no smectic phase, but a solid phase at lower temperatures. We also demonstrate that, using a one velocity model, there is no coupling under shear flow between induced smectic order and the director orientation in stationary situations thus rendering such a model to be unsuitable to describe the breakdown of flow alignment. In a two-fluid description, flow alignment breaks down and becomes unstable with regard to a space- and time-dependent state due to an induced finite velocity difference. In an Appendix we outline a mesoscopic model to account for the sign change in the anisotropy of the electric conductivity observed in nematics with smectic clusters.We report a generic theoretical framework for accurate simulation of the temporal and spatial evolution of fused fiber-optic components, fabricated by the "heat and pull" technique. The methodology is based on the solution of quasi-3D incompressible Navier-Stokes equations formulated for immiscible two-phase flow. The two-phase interface is resolved by employing an interface tracking approach combined with the immersed boundary method. The model facilitates accurate spatiotemporal prediction of the evolution of both the external shape of the optical component and the internal dopant concentration during fabrication. Validation of the model was obtained by extensive comparison to experimental results. The model was found to be a convenient theoretical tool that may reliably facilitate the design and fabrication process of a wide spectrum of optic components.