197,521 research outputs found
Ernia di Richter: a case report. Considerazioni clinico-terapeutiche.
No full text[Richter's hernia: a clinical case and the clinico-therapeutic considerations]. Fornaro R, Terrizzi A, Davini MD, Canaletti M, Baldi E, Bonfante P, Sticchi C, Cavaliere D, Ferraris R.
The authors report a case of Richter's hernia. They underline main clinical and therapeutic patterns, emphasizing the need of an early diagnosis and surgery. This is a hernia of abdominal wall with partial entrapment of bowel wall (antimesenteric site) through a small ring. The incidence increased in the last years because of diffusion of laparoscopic techniques. Richter's hernia could be asymptomatic for a long time or show vanish sign. Sometimes this hernia can be diagnosed during surgery. The clinical signs are conclamated if hernia is complicated by strangulation. High mortality is justified by performing too late diagnosis and operation
Convergence of the solutions of discounted Hamilton-Jacobi systems
No full textWe consider a weakly coupled system of discounted Hamilton-Jacobi equations set on a closed Riemannian manifold. We prove that the corresponding solutions converge to a specific solution of the limit system as the discount factor goes to 0. The analysis is based on a generalization of the theory of Mather minimizing measures for Hamilton-Jacobi systems and on suitable random representation formulae for the discounted solutions
Homogenization of two-phase metrics and applications
No full textWe consider two-phase metrics of the form phi( x, xi) := alpha chi B-alpha(x) vertical bar xi vertical bar + beta chi B-alpha(x) |xi|, where alpha, beta are fixed positive constants and B-alpha, B-beta are disjoint Borel sets whose union is R-N, and prove that they are dense in the class of symmetric Finsler metrics phi satisfying alpha vertical bar xi vertical bar <= phi(x,xi) <= beta vertical bar xi vertical bar on R-N x R-N. Then we study the closure Cl(M-theta(alpha, beta)) of the class M-theta(alpha, beta) of two-phase periodic metrics with prescribed volume fraction theta of the phase alpha. We give upper and lower bounds for the class Cl(M-theta(alpha, beta)) and localize the problem, generalizing the bounds to the non-periodic setting. Finally, we apply our results to study the closure, in terms of Gamma-convergence, of two- phase gradient- constraints in composites of the type f (x, del u) <= C(x), with C(x) is an element of {alpha, beta} for almost every x
Aubry Sets for Weakly Coupled Systems of Hamilton--Jacobi Equations
No full textWe introduce the notion of Aubry set for weakly coupled systems of Hamilton--Jacobi equations on the torus and characterize it as the region where the obstruction to the existence of globally strict critical subsolutions concentrates. As in the case of a single equation, we prove the existence of critical subsolutions which are strict and smooth outside the Aubry set. This allows us to derive in a simple way a comparison result among critical sub- and supersolutions with respect to their boundary data on the Aubry set, showing in particular that the latter is a uniqueness set for the critical system. We also highlight some rigidity phenomena taking place on the Aubry set
On the vanishing discount problem from the negative direction
No full textIt has been proved in [10] that the unique viscosity solution of
\begin{equation}\label{abs}\tag{*} \lambda u_\lambda+H(x,d_x
u_\lambda)=c(H)\qquad\hbox{in }, \end{equation} uniformly converges, for
, to a specific solution of the critical equation
where is a closed and connected
Riemannian manifold and is the critical value. In this note, we consider
the same problem for . In this case, viscosity
solutions of equation \eqref{abs} are not unique, in general, so we focus on
the asymptotics of the minimal solution of \eqref{abs}. Under the
assumption that constant functions are subsolutions of the critical equation,
we prove that the also converges to as . Furthermore, we exhibit an example of for which equation \eqref{abs}
admits a unique solution for as well.Comment: 14 page
A new material property of graphene: The bending Poisson coefficient
No full textThe in-plane infinitesimal deformations of graphene are well understood: they can be computed by solving the equilibrium problem for a sheet of isotropic elastic material with suitable stretching stiffness and Poisson coefficient . Here, we pose the following question: does the Poisson coefficient affect the response to bending of graphene? Despite what happens if one adopts classical structural models, it does not. In this letter we show that a new material property, conceptually and quantitatively different from , has to be introduced. We term this new parameter bending Poisson coefficient; we propose for it a physical interpretation in terms of the atomic interactions and produce a quantitative evaluation
On calibrations for Lawson's cones
No full textIn this paper a calibration method is recalled and applied to Lawson's cones to prove their minimality. The original proof of Bombieri, De Giorgi and Giusti is reinterpreted and made simpler
Gaussian curvature and Babuska's paradox in the theory of plates
No full textWithin the functional framework of the trace spaces of
functions on 2-D domains with corners in this paper we discuss the
geometrical reasons of the so-called Babu\v{s}ka's paradox in the
theory of plates and a few other related questions
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