1,721,129 research outputs found
: Guidelines after the 2004/40/CE European directive on electromagnetic fields in workplaces
No full text(Plenary Lecture
INTRODUZIONE DELLA LOGICA NELLA SCUOLA PRIMARIA E SECONDARIA
No full textWe present some idea on how to introduce the study of propositional logic in
primary and secondary schools in an appealing way. In particular we encourage
the use of logic puzzles and provide several examples of translating Smullyan's
logic puzzles of his wonderful book ``Alice in puzzle-land'' into propositional
logic and then use algebra to solve the puzzles. We highlight several strong points
of this approach
Sicurezza e EMC degli impianti industriali per le lavorazioni con l'impiego delle microonde
No full textSome numerical results on motion of kinks in some model of DNA torsional dynamics
No full textWe present numerical results about the dynamics of kinks in some discrete systems of equations coming from simple mechanical models of DNA, including a celebrated model of L. Yakushevich, and whose continuous limit is, exactly or modulo some approximation, the Sine-Gordon equation.
In particular our results show that the Y model improves substantially if we replace the pairing potential, which is considered harmonic in the distance between facing pairs of bases, with a Morse potential
Solvability of the cohomological equation for regular vector fields on the plane
No full textWe consider planar vector field without zeroes X and study the image of the associated Lie derivative operator LX acting on the space of smooth functions. We show that the cokernel of LX is infinite-dimensional as soon as X is not topologically conjugate to a constant vector field and that, if the topology of the integral trajectories of X is ``simple enough'' (e.g. if X is polynomial) then X is transversal to a Hamiltonian foliation. We use this fact to find a large explicit subalgebra of the image of LX and to build an embedding of R^2 into R^4 which rectifies X. Finally we use this embedding to characterize the functions in the image of L
Soliton propagation in homogeneous and in-homogeneous models for DNA torsion dynamics
No full textThe existence of solitonic excitations is a generic feature of a broad class of homogeneous models for nonlinear DNA internal torsional dynamics, but many properties of solitonic propagation depend on the actual model one is considering. In this paper we perform a detailed and comparative numerical investigation of the profiles and time evolution of solitons for two different models, the Yakushevich one and the more recent "composite" model of [1], and for two different choices of the potential describing the pairing interaction between bases (harmonic and Morse potential). We consider not only homogeneous DNA chains but also inhomogeneous ones (with sequence of bases corresponding to a real organism, the Human Adenovirus 2). We show that twist solitons can propagate in inhomogeneous chains over biologically significant distances. It is also shown that stable soliton propagation is possible for inhomogeneous chains when dissipation and an external force are present. On a more general level, our results indicate that solitonic propagation can take place in highly inhomogeneous nonlinear media
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