Boltzmann Games in Heterogeneous Consensus Dynamics

Journal of Statistical Physics - We consider a constrained hierarchical opinion dynamics in the case of leaders’ competition and with complete information among leaders. Each leaders’...     

Independence of friction self-locking from kinematic singularity

Self-locking analysis in closed kinematic chains is sometimes likened to kinematic singularity. Here a novel approach to tackle self-locking analysis due to joints friction is exploited, that is completely different from the classical kinematic analysis based on the jacobian conditioning. It is shown that an inverse kinematic singularity always entails a self-locking phenomenon because of the general increasing of joints reactions and, then, friction forces; hence, a self-locking domain can be always identified including such a locus. On the other side, this paper is aimed at demonstrating that the aforementioned condition is not necessary: namely, self-locking may occurs also if the mechanism kinematics is well-conditioned. Then, the theoretical result is clarified performing the self-locking analysis on a simple crank-slider mechanism.     

Modelling of Enzyme Properties in Organic Solvents

 In this article we review how molecular modeling techniques can be used to shed some light on the influence of organic solvents on the molecular characteristics of proteins and enzymes. Molecular dynamic simulations on bovine pancreas trypsin inhibitor, chymotrypsin, and subtilisin make it possible to get a deeper understanding into how increased intramolecular interactions improve conformational rigidity, thus explaining the lower reactivity and the higher thermostability of enzymes in non-aqueous media. The application of thermodynamics-based models allows first qualitative predictions on the selectivity of many reaction types; however, the application of quantum mechanical/molecular mechanical methods is required for the development of quantitative models of actual reactivity patterns.     

Quantum cellular automata and free quantum field theory

In a series of recent papers [1–4] it has been shown how free quantum field theory can be derived without using mechanical primitives (including space-time, special relativity, quantization rules, etc.), but only considering the easiest quantum algorithm encompassing a countable set of quantum systems whose network of interactions satisfies the simple principles of unitarity, homogeneity, locality, and isotropy. This has opened the route to extending the axiomatic information-theoretic derivation of the quantum theory of abstract systems [5, 6] to include quantum field theory. The inherent discrete nature of the informational axiomatization leads to an extension of quantum field theory to a quantum cellular automata theory, where the usual field theory is recovered in a regime where the discrete structure of the automata cannot be probed. A simple heuristic argument sets the scale of discreteness to the Planck scale, and the customary physical regime where discreteness is not visible is the relativistic one of small wavevectors.     

Free surface flow impact on a vertical wall: a numerical assessment

The sudden impact of a free surface flow upon a solid wall is a common occurrence in many situations in nature and technology. The design of marine structures is probably the most obvious example, but also river and dam hydraulics as well as the necessity of understanding flood and debris flow-induced damage have led to theoretical and experimental work on the mechanism of fluid slamming loads. This is therefore a very old and rich research field, which has not yet reached full maturity, so that semi-empirical methods in design practice are still the rule in many sectors. Up-to-date CFD technology with both Eulerian and Lagrangian approaches is employed to investigate highly non-stationary fluid impact on a solid wall. The development of the pressure wave produced by the impact is examined as it propagates and interacts with the fluid boundaries, as well as the subsequent build-up of high-pressure gradients of high fluid velocities. The geometry and the velocity field of the problem considered are very simple, but the results seem to provide new insight, in particular, into the connection between phenomena with different timescales.     

Quantum calibration of measurement instrumentation

By quantum calibration we name an experimental procedure apt to completely characterize an unknown measurement apparatus by comparing it with a few other calibrated apparatuses. Here we show how to achieve the calibration of an arbitrary measuring apparatus, by using it in combination with a tomographer in a correlation setup with an input bipartite system. The method is robust to imperfections of the tomographer, and works for practically any input state of the bipartite system.     

On the nature and the order of the deconfining transition in QCD

The determination of the parameters of the deconfining transition in N _f = 2 QCD and its relevance to the understanding of the mechanism of color confinement are discussed.