Fractal properties of relaxation clusters and phase transition in a stochastic sandpile automaton

We study numerically the spatial properties of relaxation clusters in a two dimensional sandpile automaton with dynamic rules depending stochastically on a parameter p, which models the effects of static friction. In the limiting cases p=1 and p=0 the model reduces to the critical height model and critical slope model, respectively. At p=p_c, a continuous phase transition occurs to the state characterized by a nonzero average slope. Our analysis reveals that the loss of finite average slope at the transition is accompanied by the loss of fractal properties of the relaxation clusters.Comment: 11 page

Experimental Verification of Inertial Navigation with MEMS for Forensic Investigation of Vehicle Collision

This paper studies whether low-grade inertial sensors can be adequate source of data for the accident characterization and the estimation of vehicle trajectory near crash. Paper presents outcomes of an experiment carried out in accredited safety performance assessment facility in which full-size passenger car was crashed and the recordings of different types of motion sensors were compared to investigate practical level of accuracy of consumer grade sensors versus reference equipment and cameras. Inertial navigation system was developed by combining motion sensors of different dynamic ranges to acquire and process vehicle crash data. Vehicle position was reconstructed in three-dimensional space using strap-down inertial mechanization. Difference between the computed trajectory and the ground-truth position acquired by cameras was on decimeter level within short time window of 750 ms. Experiment findings suggest that inertial sensors of this grade, despite significant stochastic variations and imperfections, can be valuable for estimation of velocity vector change, crash severity, direction of impact force, and for estimation of vehicle trajectory in crash proximity

Hyperon Nonleptonic Weak Decays Revisited

We first review the current algebra - PCAC approach to nonleptonic octet baryon 14 weak decay B (\to) (B^{\prime})(\pi) amplitudes. The needed four parameters are independently determined by (\Omega \to \Xi \pi),(\Lambda K) and (\Xi ^{-}\to \Sigma ^{-}\gamma) weak decays in dispersion theory tree order. We also summarize the recent chiral perturbation theory (ChPT) version of the eight independent B (\to) (B^{\prime}\pi) weak (\Delta I) = 1/2 amplitudes containing considerably more than eight low-energy weak constants in one-loop order.Comment: 10 pages, RevTe

Stochastic financial evaluation: The case of an intermodal terminal

Intermodal terminals (IMTs) have significant importance in logistics networks whose development enables the implementation of intermodal transportation technologies and participation in international goods flows. Developing IMT contributes to the greater use of intermodal transportation thus contributing to sustainability. To stimulate stakeholders to participate in such projects, they need to be proven economically sustainable as well. This article analyzes the financial risks of investing into an IMT in Belgrade (Republic of Serbia). The scientific contribution of the article is in being the first to use a stochastic financial evaluation model for assessing the development of an IMT. The article analyzes the financial risk probability over real-world data, considering the stochastic nature of container flow volumes and the prices of logistics services. The risk probability, as an output result of the used simulation model, is derived from the probability distribution of three distinct financial parameters – net present value (NPV), internal rate of return (IRR), and the benefit-cost ratio (B/C). The results of the analysis indicate that the development of the IMT is financially justified, with relatively low investment risk

Learning about knowledge: A complex network approach

This article describes an approach to modeling knowledge acquisition in terms of walks along complex networks. Each subset of knowledge is represented as a node, and relations between such knowledge are expressed as edges. Two types of edges are considered, corresponding to free and conditional transitions. The latter case implies that a node can only be reached after visiting previously a set of nodes (the required conditions). The process of knowledge acquisition can then be simulated by considering the number of nodes visited as a single agent moves along the network, starting from its lowest layer. It is shown that hierarchical networks, i.e. networks composed of successive interconnected layers, arise naturally as a consequence of compositions of the prerequisite relationships between the nodes. In order to avoid deadlocks, i.e. unreachable nodes, the subnetwork in each layer is assumed to be a connected component. Several configurations of such hierarchical knowledge networks are simulated and the performance of the moving agent quantified in terms of the percentage of visited nodes after each movement. The Barab\'asi-Albert and random models are considered for the layer and interconnecting subnetworks. Although all subnetworks in each realization have the same number of nodes, several interconnectivities, defined by the average node degree of the interconnection networks, have been considered. Two visiting strategies are investigated: random choice among the existing edges and preferential choice to so far untracked edges. A series of interesting results are obtained, including the identification of a series of plateaux of knowledge stagnation in the case of the preferential movements strategy in presence of conditional edges.Comment: 18 pages, 19 figure

Transport of multiple users in complex networks

We study the transport properties of model networks such as scale-free and Erd\H{o}s-R\'{e}nyi networks as well as a real network. We consider the conductance $G$ between two arbitrarily chosen nodes where each link has the same unit resistance. Our theoretical analysis for scale-free networks predicts a broad range of values of $G$, with a power-law tail distribution $\Phi_{\rm SF}(G)\sim G^{-g_G}$, where $g_G=2\lambda -1$, and $\lambda$ is the decay exponent for the scale-free network degree distribution. We confirm our predictions by large scale simulations. The power-law tail in $\Phi_{\rm SF}(G)$ leads to large values of $G$, thereby significantly improving the transport in scale-free networks, compared to Erd\H{o}s-R\'{e}nyi networks where the tail of the conductivity distribution decays exponentially. We develop a simple physical picture of the transport to account for the results. We study another model for transport, the \emph{max-flow} model, where conductance is defined as the number of link-independent paths between the two nodes, and find that a similar picture holds. The effects of distance on the value of conductance are considered for both models, and some differences emerge. We then extend our study to the case of multiple sources, where the transport is define between two \emph{groups} of nodes. We find a fundamental difference between the two forms of flow when considering the quality of the transport with respect to the number of sources, and find an optimal number of sources, or users, for the max-flow case. A qualitative (and partially quantitative) explanation is also given

Giant strongly connected component of directed networks

We describe how to calculate the sizes of all giant connected components of a directed graph, including the {\em strongly} connected one. Just to the class of directed networks, in particular, belongs the World Wide Web. The results are obtained for graphs with statistically uncorrelated vertices and an arbitrary joint in,out-degree distribution $P(k_i,k_o)$. We show that if $P(k_i,k_o)$ does not factorize, the relative size of the giant strongly connected component deviates from the product of the relative sizes of the giant in- and out-components. The calculations of the relative sizes of all the giant components are demonstrated using the simplest examples. We explain that the giant strongly connected component may be less resilient to random damage than the giant weakly connected one.Comment: 4 pages revtex, 4 figure

Evidence for a Peierls phase-transition in a three-dimensional multiple charge-density waves solid

The effect of dimensionality on materials properties has become strikingly evident with the recent discovery of graphene. Charge ordering phenomena can be induced in one dimension by periodic distortions of a material's crystal structure, termed Peierls ordering transition. Charge-density waves can also be induced in solids by strong Coulomb repulsion between carriers, and at the extreme limit, Wigner predicted that crystallization itself can be induced in an electrons gas in free space close to the absolute zero of temperature. Similar phenomena are observed also in higher dimensions, but the microscopic description of the corresponding phase transition is often controversial, and remains an open field of research for fundamental physics. Here, we photoinduce the melting of the charge ordering in a complex three-dimensional solid and monitor the consequent charge redistribution by probing the optical response over a broad spectral range with ultrashort laser pulses. Although the photoinduced electronic temperature far exceeds the critical value, the charge-density wave is preserved until the lattice is sufficiently distorted to induce the phase transition. Combining this result with it ab initio} electronic structure calculations, we identified the Peierls origin of multiple charge-density waves in a three-dimensional system for the first time.Comment: Accepted for publication in Proc. Natl. Acad. Sci. US

Passive and catalytic antibodies and drug delivery

Antibodies are one of the most promising components of the biotechnology repertoire for the purpose of drug delivery. On the one hand, they are proven agents for cell-selective delivery of highly toxic agents in a small but expanding number of cases. This technology calls for the covalent attachment of the cytotoxin to a tumor-specific antibody by a linkage that is reversible under appropriate conditions (antibody conjugate therapy, ACT —"passive delivery”). On the other hand, the linker cleavage can be accomplished by a protein catalyst attached to the tumor-specific antibody ("catalytic delivery”). Where the catalyst is an enzyme, this approach is known as antibody-directed enzyme prodrug therapy (ADEPT). Where the transformation is brought about by a catalytic antibody, it has been termed antibody-directed abzyme prodrug therapy (ADAPT). These approaches will be illustrated with emphasis on how their demand for new biotechnology is being realized by structure-based protein engineerin